Just purchased 'Torque' from the android market and bought a bluetooth OBD II adaptor from Hong Kong for £18 on ebay.
This app scans fault codes, gives you descriptions and clears the codes.
It also gives you live engine data, quarter mile times, 0-60 times, fuel pressure, coolant temp, rpm, speed and tons more!
The app was £3, but you can get a free version, so in all I spent £21 on an obd scanner than can do alot more then most budget ones!!!
Will report back when I have tested the app...
More information here