heh... evil, but it works!
generally, i'm never appealed by the "click here" or "check out my forum" links that you see scattered on other various places. and, on the rare chance i do follow thru on the link, ill just look at the board, then bounce off back to where i was.
that tactic might lead to a great "who's online" record book total, but more than likely not a high "member" count.
one strategy that works a lot better is to start up a regular conversation or debate or poll (etc) on your forums between the existing members (even if there are only 4 or 5 involved in the topic). once it gets going, post a link to that one post (not just the forum) on other boards that you're affiliated with.
that way, when guys like me feel the need to check it out, we're looking at an actual conversation, and not a forum home page. and, instead of skimming thru the various forum topics, we're skimming thru one very specific point...
that gives the reader a better chance of getting involved in the conversation, and perhaps feel so inclined to respond to it.
and, again, when you link to the thread, dont just put "click here to see this" ... instead, make sure you join in a similar conversation, and then subtly refer to your post. "thats true, cuz over
here on my forum, one user mentioned this and that" etc.
you wont get the quantity of visits brought by just mass posting your links, but you'll more than make up for it in quality -- and thats what you're after, members, not visitors.