Here's a place for C programmers to spend hours of (wasted) time.

http://www.ioccc.org/years.html

If you want to know what they do (somewhat spoils the fun of discovery, but still fun...)

http://www.ioccc.org/years-spoiler.html

The great thing about these programs is not just the abuse of the C compiler (and the rules!) but also the fact that these real programs are so small!!!!

Have fun!