Closer(ish) to home we have QuartzComposer[3] available for OSX.
I like all of these tools but can't help feeling I'd be more effective if I could just get at the underlying code half the time (in cases where that's not an option).
[0] http://vvvv.org/ [1] http://cycling74.com/ [2] http://puredata.info/ [3] http://developer.apple.com/graphicsimaging/quartz/quartzcomp...