The popular Chordbot app has been updated with Audiobus! Although I haven't used it, I've heard great things about it!
Chordbot is a songwriting tool / electronic backup band that lets you experiment with advanced chord progressions and arrangements quickly and easily.
Use it for songwriting experiments, as accompaniment when learning new songs or as a backup band for your guitar/saxophone/theremin solos. Just add some chords, select a comping style and hit play.
Chordbot creates songs by applying sequenced instrument templates to the chords you select. This gives a much more dynamic and controllable result than using prerecorded loops.
What's new in 2.0.5:
Audiobus support, "Open in" support for MIDI and WAV files, optional export fade out, general performance and stability fixes.
There are a lot of videos on YouTube for it, but most of them are terrible. For fucks sakes guys, hold your iPhone in landscape when using it to record video! Despite the troubles this causes me, I think it is a good sign to see so many terrible videos. That means it is inspiring people who are not used to making videos, to make videos showing it off!
Here is one of the better ones! This is featuring the Android version, which like the Lite version, does not have Audiobus.