• by Mark Walsh  @markfwal, April 7, 2009

Led by the wildly popular "Tap Tap Revenge," games made up 12 of the top 25 applications from Apple's App Store as of February, according to an initial comScore report on downloads and usage among iTunes users.

"Tap Tap Revenge," the "Rock Band"-like music game from developer Tapulous, ranked as the No. 1 app overall, having been downloaded by one in three U.S. iTunes users to date. Other top games included old favorites like "Hangman" and "Pac-Man" as well as newer titles such as "Cube Runner" and "Crazy Penguin Catapult."

Social networking apps also rated high, with offerings from Facebook, MySpace and AOL's Instant Messenger among the top 11. No. 2 was Stylem Media's Backrounds app, which allows users to choose from more than 5,000 iPhone wallpapers. Virtually all of the top 25 apps were free rather than paid ones.

But that doesn't mean that iPhone app users are lacking means. ComScore found they are 32% more likely than average to be in a household earning at least $100,000 annually, and more than half (54%) are in households making at least $75,000 a year.

They were also 49% more likely to visit online retail sites than average Internet users as well as spending more time on social media, entertainment, sports and search sites. That combination of affluence and engagement bodes well for marketers, according to Brian Jurutka, a vice president at comScore.

"Not only are these folks high-income, but they are also nearly 50% more likely than the average user to visit an online shopping site," he said.

The preponderance of free apps among the top 25 suggests that not charging is the best way to build a large audience fast. "One of the biggest debates in the app world right now is whether to go the free route and try to pull in ad-supported revenue or go the paid route," said Jurutka.

He noted that a small game developer like Tapulous built a big following by offering Tap Tap Revenge free and is now capitalizing on that user base by introducing specialized paid versions. They include Nine Inch Nails Revenge, which features 13 of the band's tracks and sells for $4.99.

Among branded apps, the Virtual Zippo Lighter was the only one to make the top 25, with 18% of users downloading the novelty item. Jurutka said its popularity owes in part to being among the first branded apps in the App Store. But with more than 25,000 now available, breaking through the clutter becomes increasingly difficult -- but not impossible. "One thing is that if you create something that people want, whether a novelty app or not, it will find its way around," said Jurutka.

To date, Apple says that more than 850 million iPhone apps have been downloaded from its storefront.

ComScore based its rankings on apps downloaded via PC or iPhone and iPod devices and installed on iTunes users' computers. The Web measurement firm will publish a monthly subscription-based Apple App Store Report providing information on the most popular apps and app categories and demographic and behavior profiles of users.

Beyond downloads, third-party measurement and usage data surrounding iPhone apps up to now has been limited. Last week, AdMob launched a service allowing developers to monitor when someone clicks on an ad leading to the download of an advertised application. It can also track multiple apps and conversion rates by specific ad and date.