Maybe you can look for game banner exchange sites, who also sell impressions. Like moregamers .com, arcadebanners. com, and gamersbanner. com There are many out there like these. Maybe it helps.
http://www.reachads.com/ It's CPC. They only pay 4 cents per click though. It's all picture ads. CTR for me is a little less than 3%.
I woudl try to target the audience type with CPA ads for young adults free mags, ipods laptops etc...
Yeah, I applied to them a while ago but never got a response back. Does anyone have any experience with CPMStar?