A Heretical View of File Sharing:

"But what if the industry is wrong, and file sharing is not hurting record sales?
It might seem counterintuitive, but that is the conclusion reached by two economists who released a draft last week of the first study that makes a rigorous economic comparison of directly observed activity on file-sharing networks and music buying."

This is a very interesting article. One conclusion reached by the researchers is the that many people who download music would have never bought the album in the first place. I know I fall into this category in many respects. Fortunately, we now have iTunes and MusicMatch that allows you to legally download individual songs without purchasing the entire album.