I tried Adwords and did alright, but had to remove images from my site so now I don't know if it's to possible unless you can get a low CPC.
AdWords is prettty expensive to get the traffic, but if you can get the clicks to make it work, it can be a pretty sweet deal. AdBrite is good for cheap traffic tho. I usually try to do a combo of affiliate marketing and AdSense/YPN arbitrage. That way AdSense/YPN is enough to cover the costs of advertising and the affiliate ads bring in the real money