For me, the only other one dopers would know is Reddit. I use on a once off basis a few other national forums and niche forums for various topics.
Heard City-Data is pretty popular as well as Yahoo Answers with users here. Anyone use these?
I post on a couple of martial arts forums. I also post in several of the Delphi Forums.
I was active years ago on Fark, but drifted away.
Before the Feds shut down Overgrow (circa 2006), I was very active there. If you remember Overgrow, you might recognize my username there.
I currently participate a bit on a few recreational drug forums.
I participate on city-data, which has geographically oriented message boards, as well as more general ones. Their political boards are very rowdy as they have many very conservative and liberal posters with little moderation. And overall it leans a bit conservative. But it’s the local city specific boards that really makes it.
I participate on flyertalk which is the go-to site for knowledgeable discussion about air travel, especially frequent flyer programs.
Been there a few times. Site well layed out.
I’m signed up on about a dozen automotive-related message boards, but don’t visit any of them anymore. Far too narrowly focused and all are wank-fests. I would go looking for specific answers to specific problems for specific vehicles, and almost never got any kind of meaningful responses. I get far more useable and valuable information right here.
I made a thread about it a few years ago, a rant really, but don’t want to zombie it again.
So, Straight Dope, Craigslist for free stuff and email. Very bored most of the time.
Yahoo Answers is where you go if you can’t get your GQ thread answered here. They have the best knowledge for most things.
previously.tv, with its multiple TV show and movie threads.
A good example of what I’m talking about:
Take this thread, for example http://boards.straightdope.com/sdmb/showthread.php?t=826892
In my experience, if I had posted this question on a site devoted to maps and mapmaking, I would expect the very first post to be a lengthy 4 paragraph screed roundly excoriating me for not doing any research beforehand and how I’m an ignorant nube and then the responder would go on and on and on about their vast education and knowledge and how hard they went to attain it, blah blah blah…
Then a few pile-ons, a few sarcastic “I’d tell you, but then have to kill you” kind of shit, or, nothin’ but cricket chirping.
Here, on The Dope, somebody just comes along and answers the damn question.
I don’t think that link goes where you think it does. 
This looks interesting. I’ve really been missing the IMDB message boards. Sometimes you just want to ask a question about a specific detail in an episode of some show. Or discuss some plot point. I’ll poke around there, but how would you rate the Knowledgeability/civility compared to the SDMB?
Much more civil. Don’t even try to drag another poster, or you’re out.
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One for Harley riders and another for horror movies and related things.
By “drag” you mean start a fight with?
I might need to join it. Ever since the demise of the IMDB boards, I’ve got questions and stuff I want to discuss all backed up in my psyche. It looks like the threads are about specific tv shows-- is that right?
I’m on citydata.com for my geographical area. Sometimes the “I’m moving to your area, where do I live?” threads get monotonous, so the more established posters gently point them to the previous threads on the town/area. Then you sometimes get the trollish yahoo who toss the proverbial match on a puddle of gas just to watch the fire. For some reason those threads tend to reveal the red state yahoos who like to troll the blue state boards :eyeroll:
There are a bunch of non-geographical forums there but I seldom go to them.
I used to belong to a bunch of cake decorating boards but I’ve dropped most of them because they can get really catty. I don’t have time for that. I also used to belong to Quora. I don’t remember why I dropped it.
Not as many as I used to. Pretty much the only other one right now is io9.
Snark on, criticize, make fun of.
There’s always the Giraffeboards.com.
SteveHoffman.tv, which is the best music discussion board I’ve ever found. I learned about it here on the Dope.
I almost never visit them, but I am signed up on a couple car forums and a handful of sports team forums. Of them, sonsofsamhorn.net (SOSH) for Red Sox fans is the best. They take baseball very, very seriously.