Metafilter sent me over to watch this amazing Royksopp music video (this video artist thought that it was so compelling as a straight video that he removed all of the music and added in foley--it\'s really cool).
While I was there, I found his experiments with VHS tape looping. He took a modified VHS tape, and put it in a modified video camera, which allowed him to unwind some of the tape and thread it through a VCR. The VCR was hooked up to a projector, and the camcorder was recording the wall on which the projector was projecting.
So the tape starts blank, then beings to accumulate date in a (surprisingly gradual) feedback loop. I like this sort of thing quite a lot.
There\'s a second video with a more elaborate set up, but it didn\'t work quite as well for me--probably just because of the lack of soundtrack.