Some of our advertisers require us to serve their ads from their server using embedded JavaScript tags so that they can track impressions and clicks.
My question is, how do WE track the clicks they have had on their ads, so we can tell how their campaign is going?
I think the best answer is actually the way OpenX does it.
http://www.openx.org/docs/whitepapers/3rd-party-click-tracking
Basically it searches the Javascript for the click the link and replaces it with a bounce (redirect) link that allows it track the click and still deliver the user.
It is slightly inflexible as it depends on the third party tracking code, but it is probably the ‘cleanest’ solution.