alex wrote:
there shouldn't be any popups
There are definitely popups, Firefox has blocked a few.
I run a website & fairly large forum. We experimented with various advertising networks. "Click the monkey and get a free (trendy electronics item)!" and other such BS ads made practically no money, while annoying our users and making the site look like unprofessional crap.
We ended up running prominent AdSense ads at the top & bottom of every page. They are reasonably unobtrusive, well targeted, and every day they make double our monthly hosting costs.
I'd also look into any hacks for this forum software to make it more search engine bot-friendly, or else switch to a forum that is natively designed to better accomodate spiders (such as vBulletin). We get a lot of traffic from individual threads that have been indexed in Google.