For my first project, I used SuperCollider to roughly model a Hammond organ, and used the built-in sequencing capabilities to play a piece of looping music. For this project, I decided to continue working in SuperCollider, but wanted to have real-time control over what was being played, and focused on being able to control the program I would write with a MIDI keyboard.
The version I played in class used three rotary knobs, eight pads, and 25 keyboard keys to control the program. The way it worked was to initialize several "instruments" (different drums, triggered by the pads, and simple notes, playable with the keys), and to feed this all into a delay with the feedback set to 100%, letting things get more and more distorted as the layers piled up. The first rotary knob controlled the length of the delay, while the second determined the level of the instruments going into the loop, and the third the volume of the overall track (though increasing the level in either case mostly resulted in more distortion, rather than a rise in volume).
Unfortunately, when I went to present the project to the class, the kick drum inexplicably didn't work. This came as quite a surprise, as that was about the only glitch that I had not been experiencing up until that point. Several of the other pads also malfunctioned, but luckily the keyboard (complete with glitchy, granulating pitch bender), along with the snare and hihats, worked without a hitch, and the demonstration went on without too much further embarrassment. Here's the rich text file as it stood the day of the presentation.
Here are some various loops I made at different points of working on the program. Feel free to try playing more than one at once (they're all at the same bpm), but it might get a little noisy.
And if you're just a real masochist or something, here's a longer excerpt, that starts from silence and builds up layers from there. Sorry for the abrupt ending, but this is actually from a longer, 14+ minute recording that itself started mid-improvisation, and this particular bit is the very tail-end of the recording (there's no real clean way of ending this stuff anyway, other than a lame fadeout or something. It's just the nature of the beast, I fear.).