Today I published my first Android app!
It's a starfield simulation live wallpaper rendered in OpenGL which makes use of the phone sensors to determine the virtual camera orientation. This allows the stars to always be travelling in the same direction no matter which way you hold the device. Since my phone is an HTC Tattoo, quite a lot of work went in to making it run smoothly with minimal processor usage (with the default settings it should be around 15% usage and with the minimal settings around 5%) so on any higher spec phone (especially one with 3D graphics hardware) it should have a fairly low impact on battery consumption.
More information, including screenshots can be seen on the live wallpapers page.