I use fast click context click bidvertiser and clicksor. Been doin it for a few days only so i am not too sure as to profite, in total i have made about 25$ has anyone had experience with these 4 guys. I alos usse Claxon, but they suck. And I am also an amazon affiliate! gotta love amazon.
We have used Fastclick for many years. I must say, years ago we also used Valueclick, but dumped them, and so were quite worried when Valueclick took over Fastclick.
We also use Casale Media, and have seen them develop over the past two years. But you do need to monitor the campaigns these agencies send, otherwise you can end up providing free brand advertising at the expense of paid brand advertising.