I was very excited when advertising on specific sites appeared. However I have some good and some bad results on that.
Good: some sites with gives me enough clicks and divided by what I spend, some goes below regular keyword campaign.
Bad: Can't determine what sites "work" and don't. I take a look at sites first but that's no very specific method. Some ugly sites gives me many clicks and some good looking very bad (a lot of impressions but few clicks) Since you pay for impressions, instead clicks I see the urgeny need to lear some tips to make adversiting campaigns based on specific sites sucessfull.