Officialpaidtoclick is for sale, you can find the link in my signature. Basically, advertisers pay the owner of the site (currently me) to advertise for them on my site, and then members get half of that money for clicking the links.
Once the advertisers run out of clicks, they have to purchase again, which is the advantage of having a good memberbase. We have three advertising clients, and over 60 members.
Other revenue can be made from things such as google adsense. As for my asking price - I would want no less than $150.