I just started using DirectCPV and talked to these guys at AdTechNY and they have a great network setup with some interesting traffic sources.
Essentially the traffic comes from their LoudMo Products.
So far it seems to be a decent network to try and expand on volume that you are already having success with elsewhere.
I think everyone should at least sign up and take a look around. The key is getting in early!
Use this link and the code “br25″ to get an extra $25 free added to your account.