Going over to the INTJ forum has been a breath of fresh air. It helped me to accept that I am most likely an INTJ after all (as the tests indicate.)
The first thing that struck me like a hammer was that a lot of the things that irked me about messageboards were addressed either explicitly or implicitly in their Rules and Guidelines.
1. They actually have a rule against people saying nothing but "me too!" or "+1" in their response.
I mean, it really sucks to pour my heart out to someone online, and all I get is a simple "thanks for sharing!"
2. The general tone is more serious. I can be as playful and frivolous as the next guy, but so many messageboards often lean too much to one side. The regulars have all their internal jokes with each other, and take even serious topics down all sorts of inappropriately casual avenues. It makes the discussion seem pointless if people treat it like "just another topic in which to vomit out whatever comes into my head without any serious thought."
3. I learned that contrary to common perception, INTJ's do actually have feelings (oh my!) , and yes, those feelings can run as deep as they do in their INFP counterparts.
4. Though the rules might seem to be too strict and formal on a casual glance, there is an underlying tongue-in-cheek (and dare I say endearing

) aspect to them. It's as if the moderators were self-conscious about how stereotypically INTJ it was to set up such formal rules and regulations.
5. The breadth of discussions is amazing and they are quite candid, and not afraid to show themselves in a potentially unflattering light. After all, INTJ's are their own worst critics,and take it from me, they can be harsh, merciless critics with themselves.