[gk1]

On the flip side of this is Google Consumer Surveys[0], which is actually quite useful. You set up a survey, specify your target demographics, and Google takes care of finding participants. How does it get participants? With the popups you mentioned.

[0] https://www.google.com/insights/consumersurveys/home

[smackfu]

I would hope that ads are generally useful to the people placing them.