I hope this is the correct stackexchange to post on. Seems to most relevant.

I'm looking for more ways to monetize my site. I'm already using the usual Google Adsense, tradedoublers, ad networks, etc.

What I want to know, is if anyone knows of a service/network out there (similar to tradedoubler), which allows you to accept (or bid) on campaigns (primarily CPM based).

For example: I log in, I get a list of advertising campaigns that are available and the prices they are willing to pay or I can put a bid in with imp count and cpm rate.

I'm looking for something ideally europe or UK based, but im open to others.

Thanks!