This thread's been on fire over on AA, and I feel like it's worth bringing up over here, since it's already on track to be the most arcade-accurate Pac-Man for a vintage Atari system.
DINTAR816 has apparently been working on it for a few years, and it's crazy good. He cribbed Pac-Man Dossier to make the AI as accurate as possible, and the sound effects and music are just about the gold standard for what you can do by bit-stuffing the TIA's registers.
Anyway, the ROM is available from the last post on the first page. If you have something like a Harmony Cart that will let you play this on real hardware, you have to try it.
http://atariage.com/forums/topic/229...or-atari-2600/