Max/MSP is a realtime visual programming environment for multimedia and control that's great for learning about digital signal processing, exploring new music-making ideas, hardware interfacing (everything from Wii remotes to iPhones), and more.
One of the cool things about Max is you can build software components and applications with it, and share them with other Max users. This page hosts all my Max software that I am sharing with the public.
You need Max/MSP to run this software. If you don't have it, there is a 30-day trial.
System Requirements: Max/MSP runs on OS X 10.3.9+ and Windows XP/Vista. The Runtime download page (see link above) lists the minimum system requirements, but some of these patches will require more horsepower. I have a 2.33 GHz Intel Core 2 Duo with 2 GB RAM and I still have plenty of breathing room.
For more Max/MSP goodness, check out my Max/MSP links.