Popunders are great additional source of income. When I was starting on this business, I grabbed juicyads popunder codes and placed them to my tumblr blogs. The hell, I got $30 after 3 months without even touching or updating that blog!
The sad news, tumblr shut down my tumble blog for no reason.
In regards to Plugrush, I don't think they have popunders, only pop-ups. It overlaps my page when it pops, and as far as I know, popunders are the ones that stays behind, not pops infront -- right?
