Microsoft Songsmith is a piece of software from Microsoft Reseach. It listens to you sing, takes your suggestion for the style of accompaniment and generates an accompaniment in that style, figuring out a chord progression and such based on what you sing.
There's a free time-limited version (evidently it costs $30 after the first six hours--that's six hours of actual execution time; the meter doesn't run while the program's not running or its window doesn't have focus).... and what people are doing is taking the vocal tracks of famous songs, singing them or playing them to Songsmith, and posting the results to YouTube, and the results are perversely hilarious.
If you wish to improve the tone of your abdominal muscles, this might be a cheap way to do it; I know mine are aching after listening to "Sgt. Pepper's Lonely Hearts Club Band", "Roxanne", and "White Wedding" given the Songsmith treatment. If it works with WINE, I may try some Morley, Dowland, or Machaut.