Fark.
I used to be a Totalfarker as well (a paid version of Fark which gives you access to all the submitted links). Even though I’ve been there forever (c. 2001), the flamy-ness of the comments turn me off. The threads routinely degenerate into insult-fests in no time and the moderation is spotty. That’s why I like this place. There’s designated flame areas if that’s to your liking 
Outside of the SDMB, I’m a member of some horsey-themed forums:
Arabian Horse Association Message Board: Ferrana (my horse’s name)
Chronicle of the Horse: LauRuffian
Pregnancy/child-rearing forums–I’m Ruffian at both of these:
Pregnancy Weekly
Parenting Weekly
Teri’s Message Board (GroceryGame.com…I’m a coupon/savings freak): Firefly (my other horse’s name)
Fark: LauRuffian, although I’ve only posted maybe 5-10 times.
Spine Health.com-- Back Pain, Back Surgery, and Chronic Pain Message Boards: LauRuffian
Besides SDMB,
Disney Theme Park Boards:
“Fun” boards:
“Foreigner in Japan” boards:
Japanese-language boards:
(Various Mixi groups)
www.2ch.net
*NOTE: Intentionally omitted my usernames
I’m Jragony at the Lionhead Studios Boards, but I only log in once every 6 months or so now, especially since they “upgraded” their forum software away from vBulletin after the Microsoft buyout.
I use different names on most of the forums.
This includes most but not all:
Urban75-I post there a lot
Raff-occasionally
Offtopic-I post there when I am really bored
Fark-I post here when I am even more bored
Cyclingnews forum
Road grime An Australian cycling forum
Australian cycling forums
This one. I’m also a member of The Oakley Review, a fan site/database of Oakley products, but I haven’t visited regularly in a very long time. I also used to be an occasional contributor to DDTDigest.com, a sort of pro wrestling fansite/blog, although it didn’t have a forum; the first hit if you google my name is the credits for a drinking game I helped come up with which was posted there.
ETA: Actually, my Facebook page seems to have overtaken it.
I occasionally post here and on a local community issues board but I spend most of my time at Secular Cafe.
gardenweb.com (Mostly horticulture but a few other homeowner titles.)
dbstalk.com (Quite valuable if one has Dish Network, otherwise meaningless.)
wordwizard.com and wordorigins.org (Etymology of words and phrases and word usage.)
In some of the other forums that I’m a member of, I use my real name as my username.
Secret Projects Forum
(Unbuilt projects and aviation technology)
What-If Modellers Forum
(Models and artwork of speculative aircraft, ships, etc.)
Ancestry.com
Not really a forum per se, but as much as I communicate with people there, it seems like a forum sometimes.
I 've been researching many of my ancestors, (and getting in contact with many other extended family members), from all over West Virginia, and other places as well.
I’m “Unclviny” on:
www.markii.org
www.naaminis.com
www.bmoaonline.com
www.boxerworks.com
Forums (these are the “regularly visited” ones), I might need to get a life!
Unclviny