Amanda Ghassaei has published on her website an interesting project: the Glitchbox.

This instrument can do two different things:
-it can be used as a standalone audio device, with the audio data stored in the arduino’s flash memory
-it can also be used to sequence MIDI through a usb connection to your computer

The glitchbox is an electronic instrument used for live audio sequencing. Each of its nine buttons is linked to an audio file stored in its memory, new audio files may be loaded onto the instrument via USB. A switch on top allows the user to play, record, and loop a sequence of audio. Once recorded, additional audio may be recorded and automatically looped on top of an existing sequence. Old sequences can be cleared from the instrument’s memory and replaced with new sequences live. Two knobs on top of the instrument control volume and tempo, and a second switch mutes and unmutes recorded sequences.

There is also a detailed  instructable with all the information needed.

Via:[Little Bird Electronic]