The Eternal Jukebox - For when your favorite song just isn't long enough
The Wub Machine - Turn any music into Dubstep, Drum & Bass, and more.
YOU.DJ - Mix SoundCloud music and Youtube videos live in your browser.
Madeon's Adventure Machine - Online remixing tool
Remixatron - Infinite Jukebox on the command line in Python.
The Autocanonizer - Remix your favorite song with this automatic canon creator