Songsmith will add an musical accompaniment to any vocal you supply. It analyses your vocal tone and tempo then adds a backing style of your choice. I'd like to call it clever software but to be honest I can't really think of a good use for it other than other than scoffing at its naffness.
If the whole idea of Songsmith isn't weird enough then check out this promo video for it. After watching I had to check the date to be sure it wasn't part of some kind of April fool gag.