CuteDJ - CuteDJ is the most powerful and versatile DJ software on market.
Splice Beat Maker - Make and share beats in your browser
Serato DJ - Serato DJ is award winning, digital DJing software used by professionals across the globe.
Ramsophone - A generative art/music machine. (Be sure to refresh!)
DJ Mixer Soft - DJ Mixer Professional is the best DJ mixing software for Mac and Windows, Support audio, karaoke and video mixing, automatic DJ mixing, one-click beat-matching, etc.
Google Music Lab - Interactive experiments that use the Web Audio API