Josh Spear writes CDM to point out the Optek Fretlight Guitar. (see Josh's story) It connects to your computer via a single USB cable (pay attention, Gibson) and includes light-up frets to teach you how to play.

Light-up teaching frets are a little corny (I'm resisting making a
guitar player joke here), but how about the footswitch that connects to
software to set tempo and loop points? And software integration?

Here's our challenge, more advanced players: steal this idea, and use
light-up LEDs on your guitar or synth to create beat-synced patterns to
blind your audience and send them into tripped-out seizures.