I'll be submitting it to the Google Play store soon, just waiting for some cash to come through so I can sign up as a developer.
Please let me know if you experience any weird bugs or strange things. It should be pretty easy to use for anyone who's used a digital metronome before.
Oh, I forgot to mention the keyboard shortcuts: numpad + and - to change speed, return to start/stop the metronome, and * to toggle the fourth beat beep thing.
Offline download (22MB zip)