Voxkit is a MIDI drum controller for the iPad.  The thing that makes Voxkit different is the ability to trigger notes by sound.  You can assign a certain drum sound to trigger when you clap your hands, bang on a table, etc.

Let’s say for example, you are a drummer and you want to lay down a snare roll for your groove.  Assign your snare to be triggered when you tap your drum stick on a desk surface.  Then, record enable Voxkit and start tapping out your snare roll.  Voxkit will recognize it, translate it to MIDI data and add it to your existing groove.

Voxkit also has standard drum pads you can use, but its uniqueness lies in its ability to let you trigger notes in more abstract ways.  This is a cool app worth taking a look at – especially for the price ($1).  Be sure to check it out.