There are some options. Banner/text ads, affiliate ads, sponsor ads, or inline text advertising. The inline text advertising can earn you more if your members arent paying attention to various links on the page.
Most of my earnings come from Google Adsense, but you need a lot of trageted traffic, and clicks to reach pay out.
In-line text ads can be another option since Infolinks payout is $50 compared to Adsense $100 payout which can take a long time if you are a newbie. I been usinng Infolinks for about a month about 2 months and I made almost $9.