There's Bearforest.com, which is more of an old version of Face Book (although I'm not certain, because I've never seen Face or Space Book). And there are some pay bear sites. Off hand, I would think it would be rather easy to locate the big dicked bear colonies on the Internet.
You might also check out Truckers.com, which is a semi-pay site run by a couple of real working truckers on the wet and messy side which attracts many men who might not yet know they are bears.