The number one problem with CPC advertising of Affiliate Programs is that it can be very difficult to do tests(specifically split tests) on conversions.  I've began to see a growing trend amongst digital goods providers that allows an affiliate to add their tracking code to the vendors 'Thank You' page.  Let's look at why this is necessary and how this one simple action could seal the deal on choosing a product to affiliate for.

Out of the box digital product conversions on cost per click advertising cannot be tracked.  You can of course setup an affiliate landing page and track your own CTR's and even how many outgoing clicks your links generate.  However, often times visitors do not complete a purchase, click the link multiple times, etc.  To properly track a conversion a tracking code needs to be attached to a linking page and on a transaction completion page.  Since the affiliate doesn't own the product the tracking code can not be placed on the final transaction page.

Some companies are working closer with affiliates by allowing an affiliates tracking code to be placed upon their final thank you transaction page.  One digital product of note is the wildly popular MoviesCapital on Clickbank.  They openly accept tracking codes to be placed on their pages, which can help you fine tune your Adwords campaigns.

Tracking and testing to an affiliate is priceless.  Helping with tracking, to me, is the #1 thing an affiliate program manager can do to help their affiliates.  Although on certain scales this is not possible, coming up with a method to allow this interaction could pay off in spades to the right affiliate network.