Apple App Store Developers Stunned By Success

But while many App Store offerings have little practical value, they're definitely helping to turn some developers' zany notions into cold hard cash.

Developers of some of the more financially successful App Store offerings have been surprised by the popularity of their creations, many of which are prime examples of the genius of simplicity. For example, one app named Fake Calls lets users escape boring or awkward situations by making their device ring as it would if an actual call was coming in.

Sebastian Trujillo, the developer of Fake Calls, said his goal was to make an app that would let people make graceful exits from work meetings and other dull moments that life has a tendency to throw at people.

Fake Calls lets users select the contact they want to receive the call, specify a ring tone and caller ID image, and set up a timer for when the call comes in, Trujillo said.

Trujillo offered Fake Calls for free for the first week after its release, and then started charging 99 cents per download. The paid version of Fake Calls recently surpassed the 50,000 download mark, according to Trujillo. Even after the 30-percent cut Apple charges App Store developers, Trujillo netted a tidy sum for an app that took just two weeks to develop.

Other App Store developers have found commercial success by adding functionality to the iPhone that Apple has yet to provide. Dan Walton, lead developer for the group of programmers who built Recorder, an app that turns the iPhone into a simple voice recorder, said his goal was to adhere closely to Apple's own design principles.

In Recorder, "We wanted to use as many of Apple's standard controls as possible, and for the interface to be instantly understandable, straightforward and design-driven," said Walton.

Recorder, which costs 99 cents, is now approaching the 250,000 mark in total sales. While Walton is proud of his creation, he acknowledges that the returns have far exceeded the group's expectations. "We expected Recorder to sell, but we didn't expect this much success," he said.

But when it comes to commercial success, no App Store developer's story is more compelling than that of Blimp Pilots, the group of game developers who made Koi Pond, the top-selling paid app on the App Store in 2008.

Koi Pond turns the iPhone into a serene pool in which several shy fish slowly swim around as meditative Japanese music plays in the background.

Unlike some commercially successful App Store offerings, Koi Pond has no practical value whatsoever, but that hasn't stopped iPhone users from downloading the 99-cent app more than 600,000 times since it was released last September, according to Bill Trost, a designer with Blimp Pilots.

Koi Pond took just a month to develop and began as a simple water simulation, with the developers adding fish later on as a sort of 'value-add' to justify charging for the app, Trost said. Koi Pond has been so successful that Blimp Pilots is preparing to launch a follow-up, called Distant Shore, which is aimed at the same audience as Koi Pond, he added.

"We were very lucky to get in when we did," Trost said. "We were able to establish value, and we never wanted price to be a barrier."

Blimp Pilots is trying to strike while the App Store iron is hot, but given the flood of developers who've turned their attentions to developing iPhone apps, commercial success will be much harder to achieve in the future, according to Trost.

"It's going to be harder to get noticed," said Trost. "So many people see the App Store as a gold rush that it'll be hard to sell apps that don't target specific markets."