Somebody started this game on .net a while back, and I haven't seen it here, so I think it's about time I get it started!
How it works: The first person decides the category, and the other posters work to create a list of 13 things that fit into that category. Whoever posts the 13th thing starts a new category. You should include the list in your post, please! I hope that all makes sense.
To start off:
Category: Olympic Athletes
1. Michael Phelps