We have recently added a new feature to PopAds. As an advertiser, you can now turn on Send details in campaign settings. If you do that, PopAds will add additional tracking parameters to your Url. For example, if you are buying traffic to http://www.example.com and turn on the new option, our system will send traffic to http://www.example.com/?PopAds_Website=1234&PopAds_keyword=example
This way you will be able to better track where is the traffic coming from. The PopAds_Website parameter contains ID of website in our system, which you will be able to use to change bid on per-website basis in the future. The PopAds_Keyword parameter tells you which keyword was used for matching the campaign with visitor. This way, you can track performance of keywords you are using.