If you're youngish,
http://giftedhaven.net/forum/ If you're old enough that you feel uncomfortable there, you might try the below. I couldn't tell you how active they are, or how compatible the personalities will be with you, though.
http://vcbconsulting.com/gtworld/gtadultlist.html http://mygiftedlife.org/forumThe two above I got from Hoagie's. I'm surprised Mensa doesn't have an online forum, although they have in-person meetings, so may not feel the need. I personally have not been a good personality fit for my local Mensa chapter, but your mileage may vary.
