“Songsmith generates musical accompaniment to match a singer’s voice. Just choose a musical style, sing into your PC’s microphone, and Songsmith will create backing music for you.”

Someone decided to run an a cappella lead vocal from Van Halen’s “Runnin’ With The Devil” through Microsoft’s Songsmith. The result is mind-boggling:

http://music.metafilter.com/2943/Runnin-With-The-Songsmith

(Thanks, Phil D.)