Originally Posted by stereolab

I'm not sure if you're familiar with the Co-Op but it's the best link-building network i've used so far (if you're doing mainstream). you can gradually set an amount of weight to your sites and slowly build backlinks at the pace you wish. i've tried other networks like this, but the co-op is the best i've used

http://www.digitalpoint.com/tools/ad-network/?s=14287