Finally someone made games for us programmers ;) Check it out!
Gimpel Software Bug of the Month
And if you find them to be a bit too trivial, here is a harder case (actually the post where I first found out about this "Bug of the Month" site):
Visual C++ Team Blog : Diagnosing Hidden ODR Violations in Visual C ++ (and fixing LNK2022)
That one was really tricky (I couldn't solve it), but was fun reading!
Have fun :)