SuperCollider is a realtime audio synthesis server as well as a programming language client. Client and server communicate via the Open Sound Control (OSC) protocol. The client implements SuperCollider language, a smalltalkish object oriented programming language with many useful influences from other languages like Ruby.
Over time, I wrote myself some useful extension classes for SuperCollider. Feel free to grab and use them, they're all under the GPL license, so share and enjoy. Comments welcome of course.