(YouTube link)
Released only a couple of weeks ago, Microsoft Songsmith takes your singing and creates a somewhat workable tune around it. YouTube users have fun with it by entering a cappella versions of hit songs to see what music Songsmith comes up with. The results are hilarious, like this cruise ship version of Roxanne by The Police. Pitchfork has a collection of precious Songsmith remixes, with songs by The Cars, Radiohead, The Doobie Brothers, Van Halen, and Oasis. Link -Thanks, Ron!
I feel like I'm in a David Lynch movie listening to some of them.
But, generally, the problem with songsmith is that it doesn't vary it's melodys enough. Unlike this song, most of the ones I've heard it just plays the same melody in a loop under the lyrics.