alright I`ll bite… could you explain “mine” please?
That “www” link below my post will show you my Board. It’s been up for nearly two years now, with more than 75,000 posts.
Cool board!
Dang, just when I thought I had an impressive collection of messageboards, I keep finding more and more.
No offense to you Anthracite but SDMB is still the best IMO, then again, I suppose I’m die hard about it…
Let’s see… if the SDMB crashed forever? This isn’t even the first message obard I ever posted to, but it is probably in the top four or five message boards I post to…
I’d probably spend more time on Una / Fathom / LJ, and on some other sites that I regularly visit (blogs, favorite sites, etc.
my blog
Spoz’s blog
GHQ
Kemporalia
Facts About Multiples
TechTales
Twinstuff
(there are more sites than this that I visit, as well)
Of course, I’d like to think that I’d maintain online friendships with the people I’ve come to like here through IMs, email., and such. And I’d definitely do more reading, too. That would be a plus, considering how much reading I’ve got to do in the form of piles of books on the floor. 
F_X
Preview would definitely be my friend in this case, as I just managed to fluff up three of the URLs I provided. They should be:
my blog
Spoz’s blog
Kemporalia
It’s too bad that the Subwoofer forums don’t work; otherwise, I’d probably spend some time there too.
F_X
Flamsterette_X-You know I should have figured there was a twin message board but honestly I never thought to check. Interesting…I wonder if my evil twin has posted there…
I’m registered at Fathom and UnaBoard. I lurk in both places but rarely post. If the SDMB went I’d really miss it. It’s like a really good friend to me. Not only do I feel like I personally know a lot of posters here although they may not know me from Adam some of my IRL closest friends post on this board(because of me banging on about it soooo much). I could not see how any other board (apart from the one described by Anthracite) could replace here.
Kal are you sure that shelf isn’t a mirror 
I would probably be ok after a month or so.
Kinda like a detox program.
It’s just the mental cravings for this place would be pretty intense for the first few days. then, I would become a Luddite or member of the Electric Amish and not use my computer for anything.
Whenever I see some activity from other boards showing up on the logs for my surprisingly popular webcam, I check them out from pure curiosity. Every time I gain more respect for SDMB; I think the general level of intelligence, expertise, wit, and mercifully restrained conduct here (even in the Pit!) puts this board on a much higher plane of enjoyment.
But to answer the OP and echo others, if {shudder} SDMB became no more, the first thing I would do is see if we could build a replacement from the ashes.
I post to other boards, but this one is quickly becoming my favorite. I’d probably survive without it:), but I wouldn’t be happy.
Ava
I was indeed a lurker for a long time-almost six months. In any case, i love this board and i always check in before we go for the ritual sacrifice under the full moon followed by the traditional frenzied dance to the gods of rain. Its hard to surf without electricity though…
Oh my God…how could you even suggest such a thing?
What would Echo23tc and I laugh about every night when we’re going to sleep?
What would we email each other during the day for laughs at work (ie., “have you seen this thread?”)?
I don’t post to any other message boards. Echo got me hooked and hooked good on this one. Very unique and interesting bunch of members here.
I would be very Sad:(
I would refresh the “The Straight Dope Message Board is offline forever. This is your 43,232nd visit since the board has crashed. Please do not return.” page twice every 10 seconds… just in case…
I’d spend a lot more time over at Fark killing kittens and getting a whole lot better at photoshopping.
France surrenders, I got nothin.
I’d be very sad. I’d move on I guess, but the first week or so would be very difficult. And I’d miss it even years later.