Well depending on the site there is also affiliate programs but they pay on completed actions, not just clicks. I use commission junction myself, but find that Adsense performs better, even if the page is completely related to the affiliate offer. You're also looking over stats for each affiliate program and I find Adsense more of a set it and forget it kind of thing. I mean overall I look over the stats, but I don't have to look over individual advertisers the way you have to with affiliate programs. The best advice I was given is to increase traffic where I can, and to make sure I have the ads in the best place I can to insure that they are seen.