Forum Url: http://cozycorner.smfforfree3.com
I see all these forums on great topics or just general topics and they have lots of members.... but how do they get all that traffic? I would love more members than just myself on my forum.....

Kimmie made a point about her forum being visible.
That goes a long ways towards getting people to join up and stay with you.
A lot of people do not bother when they cannot even see what is on the forum, or if they have to login all the time to read things.

It makes sense to not make a forum visible when its for things like your family,  etc (I cannot think of others at the moment but there are some good reasons)   But for the most part it should really be "out there" for all to see.

Well, one of the best ways to start off your forum is good ol' forum-to-forum advertising. Promote your website on other websites..where they allow it. That'll probably get you some starting members to make your site start off a little active.

From there try to get some affiliations with bigger sites. Contact an administrator and ask if they would be willing to link to your website(usually they'll ask you to link to theirs as well)

The main purpose behind this isn't to get members(because usually you won't get many), but to make Google and other search engines start to like your website more. The more websites that google finds your website linking to, the more Google will like you more. (And the larger the website...the more that that counts for). From there Google can start getting you members.

If you find that a member has posted something really interesting you can try to promote your website on extremely large websites like Digg.com by submitting the URL to the interesting post, then if people on Digg like it a lot you can expect thousands of hits(they'll probably be empty hits..but Google again will like you more).