Been hacking around trying to get some nifty synced visualization stuff going. Best (and cheapest) visualization seems to be Milkdrop in Winamp, so I got it responding to MIDI signals sent from Ableton Live on another machine. Here's a quick demo:

I'd like to be able to trigger video clips next, then I'm not sure about combining them all onto one display and swapping between them.

LiveAPI is an open-source third-party Ableton Live API, so Ableton Live is now hackable via Python. Create Digital Music has a write-up -- very cool.

Here's my idea: let your audience control cowbell levels of your set via text message. Make millions off of cowbell volume fights. Retire.