There's a really easy method to cheat like crazy at this game: within the Peggle folder on your computer (Mac or PC, though it's easier to find on the PC) there's a folder called "userdata" which contains all of the replays and such. Ever notice how when you leave in the middle of a game you can pick up where you left off? That's saved within userdata. If you're in a good situation (ie, triple score and flippers on Pearl Clam while going for 750k, 2 of 3 rounds beat with a good running total when trying for 1 Million, etc) just exit the game, back up your userdata folder, and continue. If you screw up the next shot, just quit out, duplicate your backed-up folder, and rename it to "userdata" again. It's the equivalent of saving your progress or using a freeze state in an emulator, albeit more manual. Note that you can actually quit in the middle of a shot and restore it (only really useful with flippers going), but depending on how fast your computer is this can end up being pointless - if it lags when you first load you're not going to be able to do much when you restore it.

Finally started doing this after trying 750k a ridiculous number of times. I knew *how* I needed to go about getting that score, but came up short by a tiny amount a few times and started doing this to beat the stupid thing. Still took a long time, but definitely saved me some frustration. :)

Note that the userdata folder is also all you need to back up or transfer when moving from one computer to another, or even from a Mac to a PC - quite handy.