I think google ads has a pay per view option, but the amount is tiny because the conversion rate is terrible. Only makes sense for sites with like, millions of page views per day.
Also, the banner doesn't seem to be working. It's showing me ads for advertising services and clicking any of them leads to an error page. I have adblock+, but it's disabled on this site.
Any pay per view we can get is preferable to no pay per view, since it takes that much more off the forum bill. If you're referring to Google Adsense, though; Google took that down from our forums a year or two ago, for legal reasons they are not obligated to disclose to us. (ref.
Xenocidius) I'm not sure what happened afterwards but there appears to have been a communication fudge on how forums should be funded, as all ads were eventually removed and we've now taken to donations or personal payments.
As far as I know otherwise, legit pay per view ad services are few and far between.
@ Antiaverage - I've PM'd you a few sites to look at.