From Lars Careliusson:
Chordbot Pro for Android is useful for songwriting experiments, as accompaniment for your guitar, saxophone, or theremin solos, or as a backing band for your shower singing sessions. Just add some chords to the chord list, select a comping style and a tempo and hit play.
What's new in this version:
Version 1.25 has fixed a copy/paste bug and added better Honeycomb compatibility.