Comment Underhanded C Contest (Score 5, Interesting) 360
I'm suprised that no one mentioned the Underhanded C Contest
http://underhanded.xcott.com/
Quoting their web site:
"The goal of the contest is to write code that is as readable, clear, innocent and straightforward as possible, and yet it must fail to perform at its apparent function. To be more specific, it should do something subtly evil. "