Feed Rave.dj songs (i.e. YouTube videos or Spotify links) and it will mash them right up. It takes a while to generate the resulting remix, but the results are fascinating and often outrageously fun.
My first failed effort: here's my mix of New Order's Blue Monday and Depeche Mode's Everything Counts in Large Amounts. I get the feeling it understands the structure of the tracks perfectly, but this particular pairing doesn't work because the superficial elements just don't mix. Most songs, even similar ones, just become a cacophany.
And then there's Rammstein vs Crazytown, embedded at the top of this post.
Then jump thirty seconds into this Biggie Smalls vs Thomas the Tank Engine pairing to get what you came for.
(The site's background video's CSS blur effect brought my late-model iMac to its knees; you can get rid of it by killing the classes added to the div id "backgroundPlayer" in the web inspector, or by not using Firefox.)