Self Tuning Guitar
I don't normally rip links from Slashdot, but this is just too cool. A self tuning guitar. It can even retune itself while you're playing it and can store 240 pre-configured tunings.
I've been informed by my friend Heff that he feels this guitar was spawned by Satan and will be the death of "real" guitar playing. That makes it even more uber cool in my book.