Popup, NO!!!
Spam, NO!!!
Banner, sure. If an advertiser is paying to advertise on a site that I like, and if I like what I see, I will check it out. I've probably clicked on 20 or so banner ads in the last 10+ years.
EDIT: And I have never clicked on one of those annoying banner ads, or the "OMG FREE BLABLA" type scam ones. Only legit ads, like ones that link to Newegg .... etc