Let Them Sing It For You (Swedish singing website)
 

This is pretty cool. Flash required.

Type in a phrase into this website and it will "sing" your message back to you using snippets from David Bowie, Chris Isaak, Frank Sinatra, and other artists.

For example.

Doesn't always work perfectly, but fun. I typed in "We Will Rock You" out of curiosity and one of the words was the actual song... funny to hear it with different tunes. I just typed in more sentences and sometimes it works perfectly... cool.