At my last job a friend and I started a running daily event called "Bug of the Day". It was supposed to be something we, or one of our coworkers, had placed into the software. Over the years we shared everything from little quirks to really nasty ugly hacks. In the end, it worked well, seeing the "Bug of the Day" and being able to laugh, and fix it, kept us all learning. I still enjoy the exercise.
And it looks like I'm not the only one. There is, ofcourse, a Blog for it called The Daily WTF. Check it out!