Who sells popunders?! Only self-serving!
 

Interested only in self serving though, where the user can chose amount he wants to serve. Targeted preferred! Please spam me!

exoclick does, but be prepared to pay for it. You can pick countries and how often you want surfers to see your ad (frequency cap) pops from lots of big tube sites

eroadvertising - lots of targeting options, pricing in euros so may or may not work for you and I think you have to have a minimum spend to have popups enabled on your account