I'm not sure how much this forum makes each month from Adsense alone, but I want to suggest a monetizing method which can help IMTalk make over $1000 each month.
I'm assuming that number because I'm alone making over $500/month with my single blog from the same method.
Oh, it isn't the 'method' actually. It's the advertising network, BuySellAds I'm talking about.
You apply with your website and they will approve your site manually.
So, what's the beauty?
You do the initial setup and forget the rest; advertisers comes in and buys ads on IMT and money gets in your account automatically. You don't have to do anything.
And yeah, for your unsold ad spots, you can display Adsense ads in that spot, too. Win-win situation
The only 'downside' you might feel is they take 25% of each ad spot sold, but believe me it really worth it.
There are lot more... Just check it out.
Good luck, Nemanja!