BuddyPress.org

Yeah, openX is by far the best the best option – If you’re smart enough when setting it all up, you’ll be able to produce some fantastic results and generate invaluable learnings on user habits which you can then use in turn to make more cash.

If you run a number of sites, it really comes into it’s own – You’ll essentially have your own ad network with the ability to gather learnings from each of your sites – find out which ads generate the best CTR’s and as a result give you more money. It’s even better if you can get pixels placed on the confirmation pages for whoever you’re advertising as then you’ll be able to work back to an average eCPM.

Oh, and you can even track adsense clicks with it too. Highly recommended.