The Google Ads seem to work much better than conventional banner ads, as they are targetted so tend to be reasonably relevant.
Judging by the number of click-throughs that we get, at least some people are finding them useful. The click through ratio on the ads at the bottom of the forum pages is low due to a variety of reasons -- lack of prominence for a start, and the fact that there are shown repeatedly as people read each thread.
Some are pay per click, some are pay per view. The payment varies from advert to advert, but each click generally pays a few pence. Obviously you should only click on adverts that interest you, otherwise it would not be fair on the advertisers who are paying.
Initial results with the adverts at the top of the page are encouraging, but are not going to be to everyone's liking. I don't think it would be right to "hold people to ransom" by demanding payment as I would much rather people only join as paying members for positive reasons.
So here's the ultimate compromise: more adverts, but you can turn them off
Opt out of seeing adverts