Nanoloop is one of my favorite apps to play with when I have a spare moment. I often try to put together a little loop or song before going to bed. Yesterday I stumbled across SoundForest and quickly fell in love. It isn't as powerful as nanoloop, but its learning curve isn't as steep. It lives happily in the middle space between instrument and toy. Here are a few little loops I've assembled using it (note, these haven't been edited into actual loops).