I don't agree with NJDavid at all. His suggestions are appreciated and were clearly well-intentioned, but I think that putting in any kind of barrier would greatly reduce the size of the universe of posters.

You have no idea how many people would simply never post in the first place if you told them in the upfront that to get a password you owe $10. Same with a snail-mail password. I do that on a lot of other boards, if it requires me to do something (even to register) that prevents me from posting or doing something right away, I don't bother.

And really, there are 1 or 2 posters every year that really cause a ruckus. It's worth the minor pain of passing by their posts to ensure that the board is open and thus attractive for the most people to post on.