Suggest me a CPM Banner Ad Network & Pop Under Ads

Hey i am currently running a football site. I get about 5000-7000 UVs a day. And earnings are about $20 from Adify. $5-10 from Adbrite. And few cents from Google.
Obviously i have given up on Adsense now. But i cant use Adify ads in all ad spaces as all the ads displayed are sometime same and makes the site Ugly.
I have 2 468*60 adspaces and want to utilize them with CPM ads. What is the best network out there? Who can pay through Paypal if possible.
& Also.
I am thinking of using Pop-Under Ads on my sites. Is it annoying for users? And what is the best Network for it?

See original post by Linkage