Anyone know any ad services for publishers that only serv ads that require participation? Like find the red dog, beat this guy at boxing, win a free ipod etc..
You are either looking for CPM ads or CPA ads. The 2 first ad networks listed here offers them type of ads and pay on a CPM basis. Most of the CPA ad networks list here offers the "win a free ipod sort of ads and pays per lead/action. Hope this helps you out and good luck with this.
The ones towards the top of the first page are the better ones. Copeac and azoogle are very good at the moment. I think that's the first 2 listed.