Once in a while I post on this place called Houston Grooves. It has a bunch of kids (actually young adults now... how time flies) who used to post at the old Astralwerks board, the first messageboard I ever posted on. It's pretty cool, because it was 5 years ago I first started talking with these (mostly) kids and now they're all grown up and out of college and doing their own thing while some are pursuing careers and djing.
I lurk at interference.com which is a U2 fansite. There's a whole bunch of subforums, everything's broken down. Don't bother with posting though. They have thousands of members there and so many people people posting at all hours, everything seems to get lost in the fray... and there's a rather frightening subforum where the google-eyed girls post which is a real turnoff... I mainly do lots of lurking about in their political/religious forum - it's pretty cool to get a global perspective on all things worldly and godly from regular people all over the world. Also lurk about to get feedback from the shows both recent and past. Brings back a lot of memories...
It's not really a messageboard, but I still belong to the old Chemical vmg mailing list - my first real interaction with the internet. Well, there's technically not a Chemical mailing list anymore - we've had to migrate and it's a pretty close knit group of us who've stuck together for a long time now. They are my first internet brothers and sisters!!