Reactable Huntemann (music) -> Free until 31 of March
for some reason, Google only gave me the link to the Mexican appstore.
This isn't the entire Reactable Mobile experience (which I have and dare I say is pretty rad); rather an album performed on Reactable Mobile which can be altered by the user using the Reactable toolset. If you don't know what Reactable Mobile is, it's the app version of an instrument known as Reactable - a multitouch table with "pucks" that serve as LFO's modulators, etc...essentially a 3 dimensional synth made for live play, with recording capabilities (in the mobile app).
Must get if you've never played with Reactable; fun even if you have it.