The G1 is built around a model of openness, enabling developers to create applications — software programs, called “apps” for short — that will succeed or fail according to the feedback from the online community. Naturally, these community-contributed programs need a marketplace where G1 users can find them, and the Android Market provides just that.

This week, I installed various applications from the Android Market on a G1 and tested them out. Google (GOOG) says it will launch with around 40 to 50 applications in this virtual store, and these and all other apps will be available free of charge from now until at least the start of next year.

BreadCrumbz makes maps.

I found these apps to be useful, entertaining and mostly straightforward. There were a few that I felt tried to jam too much into one application, such as BreadCrumbz, an app that asks users to add pictures, instructional arrows and labels to maps that they make for friends. Other apps kept it short and sweet, like Wi-Fi Toggle — a one-touch button that turns wireless capability on or off to save battery power.

The G1’s apps are more utilitarian than most apps I’ve tested for Apple’s iPhone — and not quite as visually pleasing. I even compared one G1 program, Plusmo College Football, directly with the same app running on the iPhone, and I missed the artsy touches of the Apple (AAPL) version — like menus that flipped 180 degrees when selected rather than simply opening.

One downside: Only a measly 70 megabytes of internal flash memory are reserved on the G1 for storing these third-party applications. Once you fill that limited internal storage space, you have to delete some of your apps to add more. You can’t currently store apps on the phone’s roomier removable memory card. (A one-gigabyte microSD comes with the G1.) The iPhone doesn’t set such an arbitrary limit on application-storage space. The Android Market, like Apple’s iTunes, keeps a record of each user’s installed apps so they can be easily downloaded again later at no extra charge (if they carried a fee). But, unlike the iPhone, the G1 can’t back up your apps to a PC or Mac.

The G1’s open model means extra setup steps during app installation. For example, if an application will access certain information — such as a user’s Internet connection, location data (as identified by GPS) or other personal information (calendar, contacts, etc.) — warnings appear during installation, and the user must grant permission. In addition, many apps come with license agreements that must be okayed before users can continue. If something goes wrong with an app, people can post complaints on community boards or email developers, whose email addresses appear during installation.

The Android Market home page.

To offer a general idea of what’s available, I’ve highlighted a handful of apps that I like. I broke the applications into three groups: Functional, Fun (if occasionally kitschy) and Frills.

Functional

Wi-Fi Toggle: This does what it says. Once installed, it adds an icon to the G1’s desktop that provides a quick way to turn Wi-Fi on and off without digging into the settings menu.

Locale: Like Wi-Fi Toggle on steroids, this app allows a user to set up a G1 so it dynamically changes its settings in specific conditions. The settings can respond to calls from certain people or changes in the phone’s battery power, calendar, the user’s location or the time. For instance, the Wi-Fi can automatically turn off, ringer volume can go up or down, desktop wallpaper can change or a post can be sent. Just think of all the churchgoers who could ensure their cellphone ringers are turned off on Sunday mornings or when the church’s location is sensed.

Ringdroid: Make ringtones from your own songs by adjusting bars to mark the start and end of each ringtone. Hitting Save automatically keeps the ringtone, labeled with the song’s name by default, for use on the phone.

Video Player: The G1 doesn’t have a built-in way to play videos, and this app does the trick in a clear-cut, reliable way.

Fun

Movie ShowTimes: This lets people use a finger to flick across the G1’s touch screen to page through movie poster images, titles and brief descriptions. Below each movie description, an on-screen button labeled “Showtimes Near You” uses GPS to generate lists of nearby movie times.

Pac-Man: The classic arcade game never gets old. You can move Pac-Man through his maze with one of three methods: tilting the G1 so its accelerometer moves the Pac-Man, swiping with a finger to point Pac-Man in the right direction or using the trackball to move him around the screen. I preferred the trackball.

Cooking Capsules: This program demonstrates food-making without being either too intimidating or too dull and simplified. Though there were only six “capsules” when I tested it, each includes steps for watching (an instructional video), shopping (using an on-screen list of items) and cooking (with numbered instructions on how to cook the food).

Bonsai Blast is a gaming app that’s now available for the G1.

Bonsai Blast: This colorful, Asian-themed game directs people to shoot colorful marbles at other chains of marbles, with a goal of getting three matching marbles lined up beside one another so they’ll disappear.

Krystle II: Turns your G1’s entire screen into a picture of fur that purrs and vibrates as you touch it. There’s no real point, but Krystle II is addictive and strangely comforting during long conference calls.

Frills

Ecorio: This well-intended app aims to track users’ travel carbon footprints in order to make them more responsible for the environment. It asks users to enter things like recent transit routes and carpools and suggests ways to reduce and offset people’s footprints.

Maverick: An IM program that allows people to add scribbles, location data or even photos to active instant-messaging conversations. Maverick signs users into Google Talk and Picasa simultaneously, adding IM images into an auto-generated Picasa album for later viewing.

PicSay: Add word balloons, titles, props and effects to digital photos captured and/or stored on the G1, then send the images via multimedia messaging service or email, or save one as a caller ID.

There are many more G1 apps to try, and developers are expected to keep making them for this new device. As with the iPhone, apps obtained for the G1 from the Android Market enable it to morph into a different device with different tools every day.

– Edited by Walter S. Mossberg

• Email us at mossbergsolution@wsj.com. Find this and other columns and videos online free at the All Things Digital Web site: http://walt.allthingsd.com

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It seems that this last attribute — the ability to make and receive calls on a cellphone — is overlooked and underestimated by many manufacturers. But believe it or not, there are plenty of people out there who simply want to use their cellphones for calls, period.

These individuals range from college students who frequently damage or lose their phones to wary, first-time buyers to senior citizens whose kids or grandchildren insist they use a cellphone. About a year ago, GreatCall Inc. introduced its Jitterbug cellphones, which were aimed squarely at the senior set with large keys, a free operator service and the phone’s own number prominently displayed on a sticker.

It seems that GreatCall was on to something. Verizon Wireless recently followed the company’s lead by introducing its straightforward, no frills Coupe, a cellphone that offers many of the helpful traits found on Jitterbug phones, like large screen fonts, but without a lot of extras. Verizon simultaneously unveiled two calling plans designed specifically for seniors, and was followed a month later by AT&T and its own monthly plan for those 65 and over. AT&T also has an uncomplicated phone of its own in the works for 2008.

This week I tested Verizon’s $40 (with a two-year contract) Coupe (www.verizonwireless.com) against GreatCall’s $147 Jitterbug Dial (www.jitterbug.com) to see how the two stacked up. I found the Jitterbug more comfortable to use for longer phone calls because of its cushiony earpiece, which blocks out external sound and helps the phone rest easier between your shoulder and ear during conversations. And Jitterbug’s mantra of simplicity will appeal to cellphone newcomers.

But for those who have been using cellphones and are familiar with the way they work, Jitterbug’s nonconformist features — like Yes and No buttons in place of Send and End and the use of a dial tone whenever the clamshell-shaped phone is opened — can come across as too basic, to the point that they’re confusing. One example: many standard cellphones redial the last number called when the Send button is pressed twice, but redialing on the Jitterbug requires navigating through five screens to redial the last number.

The Coupe is the smaller of the two and blends in with other cellphones. It includes a few of the extra functions found in normal mobile phones, like an alarm clock, calculator and the capability to send and receive text messages; perhaps most people who buy the Coupe won’t use it for texting, but it’s nice to have the built-in option. (The Jitterbug doesn’t have any of these features.) Right now, this cellphone only comes in shiny black with a blue border around its outside display screen. An included charging cradle adds a touch of convenience.

The Coupe also has some fun features that give it a more personal touch, including a choice of 24 ringtones and 10 wallpaper designs for the main screen’s background. After seeing low-grade camera lenses on nearly every digital device that I’ve picked up recently, the Coupe looked a little naked without one.

Three red buttons labeled I, C and E (for In Case of Emergency) are positioned just below the phone’s screen and can be assigned names and numbers to work as shortcuts to those most often called. A specially marked “911″ button on the phone’s keypad is designated specifically for emergencies, though this must be held down to use and, even then, asks if the caller definitely intended to call 911.

A speaker button is also clearly labeled on the Coupe’s keypad, and pronounced volume adjustment keys line the phone’s side. On-screen fonts appear larger than those found on regular cellphones.

Verizon’s well-known network is sure to be a draw for potential buyers, especially because any plan used with the Coupe includes free calls to other Verizon Wireless users. Though any of this carrier’s plans work with this basic phone, the Nationwide 65 Plus plan made its debut with the Coupe in hopes of appealing to those ages 65 and up. A single-line plan allows 200 anytime minutes and 500 night and weekend minutes for $30 monthly; the two-line plan offers roughly double the minutes (to be shared) for double the price. These plans aren’t exclusively usable with the Coupe.

GreatCall’s Jitterbug comes in two $147 models: the Dial, with a numeric keypad and the OneTouch, with just three large buttons labeled Operator, Tow and 911. I’ve tested both in the past, but this time around I looked at the Dial because it’s most comparable to Verizon’s Coupe.

The Jitterbug Dial phone comes in black or white, and its buttons and all of its on-screen lettering appear considerably larger than the Verizon Coupe’s. Its number keys glow bright white and are encircled by yellow borders, while the Coupe’s digital keypad is black with glowing blue numbers — colors that aren’t as distinctive. Unlike the Coupe, Jitterbug doesn’t come with a charging cradle, though GreatCall has plans for adding cradles in 2008.

A free operator service can be reached from Jitterbug phones by pressing “0.” This operator greets users by name, places calls on the user’s phone (saving you the trouble of dialing) and can add numbers to a phone’s contact list if a user doesn’t want to or can’t do this.

The Jitterbug can be pre-programmed with names and numbers; I ordered mine with five pre-programmed numbers, a luxury that nervous new cellphone owners might find worthwhile. Things get difficult when you try to enter your contacts. Even though each number key has three or four letters assigned to its key as on all phones, adding a contact involves using Jitterbug’s clumsy system of choosing one letter at a time from the screen. You’re better off using the free operator service for this.

Jitterbug phones let users store only 50 contact names and numbers, while Verizon’s Coupe will store 500. Many first-time cellphone owners will be content with 50, but, again, options are good.

The Jitterbug and Coupe each have small screens on their outer shells that display the time, date and phone numbers of incoming calls. But the Coupe displays its remaining battery power both on this outer screen and inside on its main screen, while the Jitterbug only flashes battery status on the screen if the battery reaches a certain low level, or if you navigate to a special “Phone Info” screen.

Behind the scenes, GreatCall’s Jitterbug phones run using networks set up by other carriers; I never had any trouble dialing out or receiving calls. A variety of calling plans can be used with Jitterbug phones ranging from $10 monthly for pay-as-you-go at 35 cents a minute to $80 monthly for 800 minutes. Add-on packages of minutes and sharing plans are also available.

If you’re familiar with cellphones, the Jitterbug will be a confusing step back for you, even though its free operator service and comfortable earpiece are pluses. Some people will prefer the Jitterbug’s larger fonts and number keys to the Verizon Coupe’s smaller, more stylish build. Still, the Coupe is a good option for people who have at least some familiarity with technology and cellphones. Each in its own way does a good job of sticking to the basic task of handling phone calls.

Edited by Walter S. Mossberg

Email mossbergsolution@wsj.com.