One thing I do is when I get an email from a friend that I want to forward on to other friends I put my sig on the bottom of it that has my website links in it. Hopefully that will encourage my friends to visit my sites now and then too to see what I've updated on them.

I also write my forum website address at the bottom of my return address on all my snail mail.

I have one forum for all my websites ( and my friend's web sites ) rather then a separate forum for each site, no one ever joins or posts but me but I get a lot of traffic to it, but they don't seem to click on my ads. I'm not really sure what they do there... People don't seem to join multi-topic forums, but I do get a question now and then from someone who visited one of my sites then that gives me new ideas for content by finding the answer to their questions.