It all depends on traffic but forums in general are a little bit tougher to monetise from as they have more regular traffic rather than the pass on through type which is more likely to click on your ads... Man you have way too many ads all over the place.. Lose those interstitials..
Man your website is messed up. you have ads overlapping your text, and the website looks like it was made 5 years ago. its all greys and blacks. not good at all. you need color. your adverts are even grey. and in firefox its messed up. you gotta seriously rethink this before you continue.
Remember folks, traffic = money. The more traffic and the niche of your site - whether its high paying or low paying, the more money you'd make.
I love these questions. Honestly you have a MUCH better chance of making money if you pick something you love and work on the content. The money will follow once you have a user base. A site I sold back in October '06, all I did was build a site on something I was interested in, did basic marketing (sitemap, SE submission, directories) and then focused on the content. Three months later I had roughly 61,000 backlinks, 10k visitors a day, and was making $200-250 a day. I used no fancy tricks, no black hat or programs, and definitely no ebooks. Read DP, build a site you are interested in, blend ads (lightly, don't overwhelm) and the money will come.