A good article about PURLS:

In a recent blog post from TargetMarketing.com, Ethan Boldt discusses some interesting points about PURLs as a follow-up to a webinar he had. His discussion on the location of the PURL was interesting. However, in several places, Mr. Boldt makes the important point – PURLs are not magical. Simply slapping one on a marketing piece does not instantly increase responses. The bottom line is that all of the traditional marketing concepts remain at play: You need to understand the audience that you are speaking to, you need to speak to them in a relevant way with a message about their needs, and you have to give them an incentive to want to take action with you.

The full article can be found at: http://www.targetmarketingmag.com/article/purls-5-things-you-need-know-about-personalized-urls