Rok Hastrik, author of 'Unleash the Marketing Power & Publishing Power of RSS', has written up a good case study on how not to implement RSS.

The subject of the piece is AdAge.com, a marketing publication.  Bottom line? If you try to subscribe to their RSS feed you'll get this - a registration invitation with zero value proposition.  Given this is a marketing industry  publication for markters, I suggest they read Rok's advice and republish the article in their next edition...oh, and change their RSS plan.