Sarao, get yourself a list of high paying keywords (paid or free). Look at the amount advertisers willing to pay for each keyword. Select a keyword and create a category where people can discuss anything around that keyword. For example, on your regional forum, why don't you create a category on mortgage or insurance. And ask people to discuss anything related to mortgage/insurance in that category. Watch the adsense ads in that category. They are of higher paying ads. Adsense is indeed really weird but intelligent.
Learn about channels and how to test the your ad units, it's very useful information: https://www.google.com/adsense/support/bin/topic.py?topic=152
Those are some pretty low payouts but my first inclination is that either your on-page SEO is off and you're showing irrelevant ads or you picked a niche with low competition/advertising competition. Try a shot in either finance/mortgage/insurance/healthcare for better payouts. Hope that helps!