Check out the Optimus Keyboard. It’s very cool. Each key is made up of an array of OLEDs so that they can change function for various programs. Unfortunately it doesn’t exist. The site says it is supposed to be released in 2006 but that could be optimistic.
The StroboPick is a small guitar tuner in the form of a guitar pick. Rather than measuring the frequency of the sound your guitar makes, the strobopick is like a miniature strobe light that allows you to see when the string is vibrating at the correct pitch. This allows you to tune extremely accurately and also has the advantage of working in noisy environments
The JamPod is a cool little accessory for you guitar and iPod. It’s a tiny little guitar amplifier that sits on your iPod and allows you to jam with your guitar to music on your iPod through your headphones. I thought this was a fun thing so I pre-ordered one back in March of 2005 for $29.95. The current price of the JamPod is now $39.95.