Any specific ideas on how to do it?
For an instance if you search vegan talk
in google vetalk.org is the first but it is still not popular for some reason.
It doesn't come up when searching "vegan forum" or "vegan webboard"........the other popular ones do.
I would read the link I originally posted.
You have to work at it, announce the existence of the board everywhere you are welcome to.
Doing something different would help.
Too many webboards are either too restrictive or too permissive.
There is no software out there that is starting to put more filtering power in the hands of the users to let them do it themselves.
I think that combined with a LOT of grass roots advertising will help.