In this video, we check out a simple Android Live Wallpaper called Space Junk. It has a cartoonish space setting and features an astronaut armed with a gun. You can get him to shoot floating objects, or space, junk by tapping on them. Get Space Junk Live wallpaper in the Android Market for free. If you want extra customizing options, you can buy the full version for 99 cents.
Also have a look at Dynamic Paint Live Wallpaper.