DENVER (Billboard) - Offering 150,000-plus apps that have been downloaded more than 2 billion times, Apple's App Store is far and away the leading source of mobile applications driving today's mobile entertainment market.

But who is No. 2? A little-known startup called GetJar, founded in 2004 in Lithuania.

Now based in San Mateo, Calif., the company has 68,000 free apps that have been downloaded about 900 million times, and it's planning to launch a paid app system around midyear.

By way of comparison, Google's Android Market has close to 50,000 apps with about 40 million downloads, while BlackBerry has slightly more than 6,000 apps. (Download figures aren't available.)

Unlike those app vendors, which are each dedicated to a single mobile operating system, GetJar distributes apps for multiple platforms and devices. That's what makes it interesting for artists and labels as they look to maximize their reach among mobile consumers.

While many players in the music business are content with creating apps for the iPhone, the fact remains that many consumers don't own one. Independent app stores like GetJar make it easier to reach other mobile subscribers by aggregating apps for different phones at one location, saving companies the trouble of creating different marketing efforts for multiple devices.

When GetJar customers select an app to download, the site automatically detects the type of handset they're using. If the app is compatible with the handset, GetJar serves up the appropriate version of the app, whether it's for a BlackBerry, a Nokia phone or an Android-based handset. For iPhone users, it redirects them to the Apple iPhone App Store for downloads.

We're the Walmart of app stores, GetJar chief marketing officer Patrick Mork says.

GetJar isn't alone. It's merely the largest among a slew of independent app stores that include Handango, acquired earlier this year by PocketGear; Handmark; AppBoy; and Mogango.

What makes them particularly compelling is that they offer apps for devices other than smart phones. Called feature phones by the mobile industry, these devices contain Web browsers and multimedia capabilities but don't have the same screen size, processing power or custom operating systems that are the hallmarks of the smart-phone category.

In fourth-quarter 2009, only 21% of U.S. wireless subscribers were using a smart phone like an iPhone or a BlackBerry. While that's up 14% from the same period a year earlier, according to a recent report by Roger Entner, senior VP in the telecom practice at Nielsen, it still means 79% of available phones today are feature phones.

About 60% of the apps downloaded from GetJar are for these types of phones. If a participating developer doesn't have an app than can run on a GetJar user's phone, the service instead provides a downloadable shortcut to the mobile Web version of the app through the feature phone's browser.

App developers are mindful of the fact that many consumers using entertainment apps are replacing their feature phones with smart phones. A recent comScore study tracking mobile gaming use found that U.S. mobile users with feature phones played mobile games 35% less last year than the year before, while mobile gaming on smart phones increased 60% during the same period, credited primarily to the fact that mobile gamers were shifting to smart phones. And thanks to falling prices and the expanding capabilities of the devices, Entner projects 51% of U.S. wireless subscribers will be using smart phones in third-quarter 2011.

But that means feature phones will still make up about half of the U.S. market in two years -- and will retain a greater presence in emerging international markets. For developers that focus on a single platform, such as the iPhone, GetJar isn't a top-of-mind outlet.

Still, it's proved effective for app developers looking to maximize their reach. Mobile instant messaging app Nimbuzz, which was one of the first apps available on GetJar when it launched, credits the service for more than 30 million downloads.

GetJar provides app developers with an additional distribution channel at little to no cost. It charges nothing to post an app, and developers can bid auction-style to have their app promoted on GetJar's home page.

As walled-garden app stores like Apple's App Store and the Android Market get more crowded, independent aggregators like GetJar could become more valuable to artists and labels that are trying to reach mobile consumers.