<a href="http://www.baen.com/library/intro.asp">The Baen Free Library</a> and Baen's online store are a great example of how to do things right. You can even download the free books without having to 'buy' them. Some other sites make the user go through the entire checkout process to 'buy' an item for $0.00. Though the disclaimer at the top of the intro page is a little disappointing: <em>"As a result of our decision to sell our titles at third party vendors, we have had to remove some titles. Others are undergoing alteration and will be brought back into the Library over the next few months."</em>
Thanks for writing this up for those of us who had to 'attend' OSCON vicariously.