i know dfx has been named before, but this in particular is so good:

dfx Buffer Override



Buffer Override can overcome your host app's audio processing buffer size and then (unsuccessfully) override that new buffer size to be a smaller buffer size. It makes a lot more sense if you just try it out and hear what it does. It can sound like a stuttery vocoder or a stuck beat shuffler or many other delightful things. In certain hosts, you can also "play" Buffer Override via MIDI notes and even sync it to song tempo.

http://destroyfx.smartelectronix.com/

http://dfx.spacebar.org/p/bo2-win.zip