I once developed data backup software and paid $500/mo to website owner who had great blog articles on backup tools and technologies to put on my gif banner ad.

I once developed data backup software and paid $500/mo to website owner who had great blog articles on backup tools and technologies to put on my gif banner ad. This was win-win for all. I made tons of sales from there. So my suggestion is to work not on website that is good for ads, but on website that is good to deliver information and answers on questions. Ads and referral sales will come after that.