I find it fascinating that there are so many tiny details and variations between levels, which apparently are essential to memorize in order to achieve "perfect play".
The learn mode is very helpful (try it at http://shaunew.github.com/Pac-Man/ ). It graphically shows the strategy each ghost uses to catch Pac-Man. Outside of aficionados, not many people realize how intricate the behaviors and quirks are. Very neat.
I find it fascinating that there are so many tiny details and variations between levels, which apparently are essential to memorize in order to achieve "perfect play".