A group of cool cats has figured out how to add new textures and other mods to cars and buildings in the Android version of Grand Theft Auto 3. The XDA Developers forum is a good place to start for mod file downloads and the files can be inserted in the sdcard/android/data/com.rockstar.gta3/files/gta3/ directory (which happens to be the same directory structure as the PC version). Click the break to see a video of one of the car mods in action and remember, your ride isn't ideal for drive-by shootings unless Xzibit says so.

Update: Jim wrote in to say that the iOS version works as well!