are the destination pages on your site or offsite?
if they're onsite, it's easy enough; have a chunk of php on the target page that increments some form of counter.
if it's offsite, you have to be slightly more cunning; rather than send them straight to the destination, send them to an intermediate page (which need have nothing but php code on it) (passing it the destination url, obviously) which increments the counter and then redirects them to the destination. you can do the same thing with cgi, also.
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rad