Bruce Schneier has a short entry about Dungeons and Dragons and the Israeli Defense Force. Apparently having played D&D causes the IDF to lower the security clearance level you can get.
I and many of my friends played D&D when we were younger. I know a few who still play a weekly game. Several of them have very high security clearances. One is training to become a Fed at one of the alphabet agencies. All of them are very well grounded individuals.