I'm having quite a bit of trouble finding pay per click ad networks that have the following criteria:
1. You can have complete control over which adverts you show and where. I don't want a network where I drop in some js and it analyzes my page, because that isn't appropriate for webapps. Ideally I just want an inventory of adverts that I can handle myself.
2. You can update links etc in realtime. (via DOM manipulation)
I'm really surprised google adsense doesn't have a product tailored to ajax type applications yet. For a webapp where you don't have any page reloads, the existing google adsense is pretty useless.
If anyone knows of any networks I'd be really grateful. (At the moment using cj,linkshare,clickxchange,and a few uk based ones, but these are mainly lead based).
If I can't find one I'll probably end up making my own and having advertisers come direct etc, but this would be a bit of a diversion if there's already some out there.
Let's say you use some sort of program and get paid per lead - I would suggest CJ/Linkshare/Neverblueads[1]. Then track the ads well, see which work and fit in with your site. Look for a clickthrough rate of at least 0.10% (although depending on how you display/cycle the ads this could be off). Then from there look to have a conversion rate of definitely better than 1/10, aim for about 1/3.
If you work in those numbers (probably your first attempt will be about half that), you will make more than PPC. You will also completely control how you serve ads and not be bound by the conditions of something like adsense.
I used to work for a major website, and they tended to make more per click on their ad campaigns that were revenue sharing than PPC as well.
Because of how behind the times the ad industry is in terms of AJAX sites, I really doubt you will find someone who allows you to change the ads in the method you desire.
[1]http://www.neverblueads.com/signup?ref=aff_66639 if you want to signup (that would give me a referral). It is pretty highly rated.