I am running a very possibly profitable cpm and cpc ad network. The site is cpmfusion.com, I made it about a week ago but I don't have time to work on it. It has amazing potential and I am looking for someone to take it over and split revenues. Email me if your interested at contact@cpmfusion.com and We will work something out.
If you have a decent site someone might buy it from you, but I doubt someone is just going to jump in and give you a free ride.