I've written my first Android app, a gas mileage tracker called "Gassy Girl" (I'll leave it to the reader to decide how Henrietta-inspired the name is).

Archive containing source, readme, GPL v3 license, and apk file: GassyGirl-1.0.0.tar.bz2
Apk file (for straight download from an actual phone): GassyGirl-1.0.0.apk

I'll probably add some new features to it over time-- maintenance tracking and oil change reminders are two enhancements I have in mind-- so expect new blog posts when/if I create new releases. I also might add the app to the Android market, but I'm debating whether Google's $25 registration fee is worth it.