I’m interested to know what other web forms people frequent, if any (I know I know, the straight dope should be satisfying enough for everyone 
).
Myself I very occasionally go on the Guardian online talkboards - http://www.guardian.co.uk/index/talk/
I also belong to www.satannet.com, a message board for Satanists. Not a place for the foolhardy, I have to say.
www.youthink.com
www.no-duh.com
That’s it!
I hang out on Apolyton irregularly, usually in this forum. I also participate in a forum for my psych class, which is amazing- I get graded on my ability to shred people’s message board arguments while using good grammar and spelling. I love that class.
Absolute Write. That’s it. I may browse other forums as I come across them, but I haven’t found anything else that I hang out on consistently.
http://community.livejournal.com/scans_daily/ (okay, not strictly a message board - scans from comics)
Most of them are related to Australian railways, so I doubt would be of interest.
No, my mum doesn’t dress me funny. 
The only other board I post to is an actuarial message board. Yes, it’s as nerdy as it sounds, and no, I’m not going to link to it, because an outsider reading our prattle about the upcoming Advanced Ratemaking Exam would soon be in a catatonic state.
Other message boards? I don’t understand the question. 
I was mostly a Fark lurker before I was introduced to this board. Once I signed up here, Fark got a lot less interesting. I quit paying there and haven’t really been back since.
urbanplanet.org, specifically the Grand Rapids fora.
trekbbs.com: Star Trek board
the-w.com : Professional wrestling board
p075.ezboard.com/bvalis22074 : General interest / sci-fi board administrated by a fellow Doper. It was my introduction to this community.
And though it’s not a message board, I’m pretty heavily involved in livejournal.
DIGG.com…of course!
Colorado AR-15 shooters club discussion forum.
Used to hang at the SciFi channel Battlestar Galactica board(s), but that didn’t last.
I lurk on (in? at?) many boards, but I only belong to The Dope and half a dozen rock band-related forums.
Hi Loaded Dog, too bad about the EZ Board. Try FARK, same idiots, canadians, english and a lot of kids living in their parent’s basements.
I’ve been enjoying Fathom more and more lately. Handing out noogies and all. It’s OpalCat’s message board.
I also lurk at two other places, one of which is Wackbag (Opie and Anthony Show message board, it wouldn’t be any fun if you didn’t listen to the show).
I have managed to compile 10k posts at www.twoplustwo.com. They are the biggest of the poker message boards.
Especially in the last few days with revelations that there was widespread cheating at one of the largest poker sites.
I have an account at Fathom, Skip’s MagicBoard, and pjeoq a6essaw, all tangentially related to the SDMB. The only one I’ve been really active on lately is pjeoq a6essaw, though. Oh, I have an uncle who runs a private messageboard for the family and a friend who runs an unofficial messageboard for my high school.
The dope is the only board I post to.
The only other websites I frequent is Fark, Snopes, and Filthy Critic.
I used to like to go to a certain board that shall remain nameless. I started posting there and was promptly chased away. There was some serious hive behavior going on there, and I made the mistake of disagreeing with the Queen Bee.
They basically kicked me off the board. I still like to visit the site every now and then, because the content is really funny. I wonder if the creator of the board even realizes how crazed the posters are.
I used to like Maddox’s site, but he doesn’t post much anymore.
Too bad? Huh? You mean G’Dope? Naah, that’s still going fine. It moved away from being an SDMB spin-off though, which is OK - a natural progression. I handed it over to somebody else so I could concentrate on other things, but I still post there.