Apple's App Store has been a tremendous hit since it was launched about 5 months ago, and Apple's year-end charts (iTunes link) show that iPhone and iPod Touch users are turning to gaming and entertainment programs.

Games dominated the most-downloaded paid applications list, led by the Zen-like Koi Pond. Apple's own Texas Hold'em, Crash Bandicoot: Nitro Kart 3D, Super Monkey Ball, Cro-Mag Rally, and Enigmo also ranked high on that list. The iPhone 3G has proven to be a strong gaming platform due to its touch screen, strong processor, motion controls, and graphics capabilities.

On the free side, the Internet radio program Pandora was the most-downloaded app, followed by a mobile Facebook program. Despite being out for a little more than a month, the Google Earth program was the seventh-most downloaded free iPhone application. Other programs on the list include AIM, Tap Tap Revenge, Urbanspoon, and Lightsaber Unleashed.

The success of the App Store makes the iPhone an attractive and potentially lucrative platform for developers, but Apple has faced some criticism over its control of the marketplace. Some developers say Apple's approval process is unclear or unfair in its vetting process. For example, a joke app called Pull My Finder was pulled from the store for no clear reason, but Apple has allowed Google's voice search app to remain in the store despite it using an undisclosed iPhone API.

But Apple has been making some changes to make the App Store more developer-friendly. It recently tweaked the way applications are reviewed and listed in the store, and it's moving toward letting developers offer free trials.

The success of the App Store has not gone unnoticed by Apple's rivals. Google has taken a similar approach for downloading programs to Android-powered phones with the Android Market, Research In Motion will open its own online application storefront for BlackBerry devices next year, and rumors persist that Microsoft is preparing an app store for its next version of Windows Mobile.