Mac OS X uses emacs as a text editor, which contains a number of hidden games including Snake
and a whole slew of others. Follow the simple steps included here
, and you could be playing a boatload of games that you didn't even know were on your Mac. Granted, the games pretty much suck (the graphics make the Wii look like Super High Definition 2160iii), but if you're trying to kill 30 minutes while sitting in the library, look no further.
We're still exploring these and trying to figure out what the heck some of the games are.