I've spent the last two weeks taking a segue to learn how to develop applications for Android phones. I just gave a presentation last night to the Seattle Google Technology User's Group. If you're interested in getting started with Android, I pass on some general tips for the beginning developer.
My friends know that I have an interest in antique computing devices, and in particular, the German Enigma machine. I thought it would be cool to make a very realistic simulation of the Enigma that I could run on my phone. After two weeks of work, I finally published my Pocket Enigma Machine into the Android market - and sold 6 copies in the first 12 hours!