I've definitely heard of the double-shot trick. VERY useful. I don't consider that "frying" however.
Another frying trick:
MOUSE TRAP
Not really useful since you can't finish a screen. But it is interesting. Frying at the start of a game (which oddly enough begins immediately after you power on the console) until a death seems to have happened (the "mreow" sound of a cat killing your mouse) seems to remove a lot of the cheese pieces in the maze. The walls in the center section seem to be invisible. Also, the cats may not be able to move! Unfortunately even when you clear all the cheese pieces, the screen can't be beaten. And it's not like there's invisible cheese you can eat-- the screen just can't be completed. Oh well, kind of interesting.