I was browsing Slashdot late last night and came across a rather amusing bit (to me at least) about an OpenBSD developer who fixed a 33 year old bug in a core UNIX library. It's a pretty geeky read, but I think it's rather funny on the count that it took that long for someone to even notice the bug in the first place!
http://bsd.slashdot.org/article.pl?sid=08/07/08/2236232
What's especially of interest is the manner in which the bug was found and that was mostly by accident!