If you're getting residual revenue on a website, at some point someone's going to figure they could get a bit more residual revenue by adding some ad scripts, and pretty soon you've got an entire stack for serving ads that needs maintenance and ROI.
I just let Google do that. Sure it's not max possible value, but return on effort is pretty good. Advertisers can buy through google and target your site. If you get enough traffic, you can probably cut a better deal (ok, that costs negotiating time, but if the ROI is there...)
