I could have the macro load a .jpg or .bmp to the Internet then download it then re-upload it and see what kind of glitches pop up in the image after several thousand cycles of this and on and on.

Or converting audio back and forth between various formats. I've heard of people doing that before, but I would just do it to try to get effects on the sound that are inherent to the conversion/compression.

I got my tremolo pedal yesterday - so useful and quite a lucrative purchase. At first, I played guitar though it and was like... oh, then I turned down the rate or whatever and played keyboard sounds with sustain through it, cuts it on and off rhymically.