How about including a survey option in new posts? It would be interesting to see some numbers on how often people visit, which forums, etc. I know there'd be some dangers but with administrator's rules and power of veto I could see it being a great tool. I frequent a marathon site
Hal Higdon - Time-Tested Training Programs for Marathons & More and if you go under virtual training, he has a great example of a survey option in his forums. You'd have to sign in under guest. Look for a little bar graph beside the title that indicates it's a poll.