______________________
Affiliates

to implement link tracking, I've used a LAMP stack (lack of choice from customer). the tracking worked in a way similar to google-analytics:
- in the affiliate page, insert a reference to a remote js, specifying ID of the site (yes, generate a custom JS for each request related to an affiliate site). the js can eventually load an image (for example a banner) working on the page DOM (that's why there's a custom generated JS).
- the system gets the requests and save the record. if there's a cookie, then check the record on db for eventual UPDATES instead of INSERT (speacking in SQL terms). saved referer too.
- every 10-15 secs, the JS make ajax update request, so there's a track of time per page.

I've worked on the analisys and first core implementation of that system (http://bit.ly/1c1Pk1), then I left the job to others (I was a consultant) . I know it isn't the best way of doing link tracking, but it worked very well (seems that the official launch will be during the next weeks).

if you want, we can talk about it more in detail

cheers,
apeacox