Adbrite is the best by far, for proxies anyways. They pretty much don't have any rules so you can do almost whatever you want with it, including put it on proxified pages.
Adbrite is the best, their rules are really lax, and there is no site approval period, just set the ads up, place the code, and go. You can even maximize your earnings by playing with which publishers you approve/dissaprove.
thanks for the info I was looking at this as well. What is their standard rate per cpm? Do you have to get a certain amount of CTR as well?