"Jazzkeys" was created by Plan8, a design firm that does music/sound for brands, film and interactive what-have-yous.
It's a word processor that plays music as you type — each keypress is translated into a piano note, which the software strings together in a vague improvisation, in realtime.
When you're done typing a message, you can click the little arrow to the far right and generate a link that you can send to someone; it'll play the message back, showing each keypress one by one, with the same speed and cadence that you originally typed it with. (Here's me typing that message you see above.)
It would obviously drive one batty to type, like, a novel using this sort of thing — but hey, if someone wants to do it and send me the link, I'll watch it!
Generally, though, I highly approve of this. I really dig funky and playful experiments with word-processing — a field that otherwise has seen shockingly little innovation in decades.