I claim that one of the best features you could add is a feedback mechanism in the site. At the minimum, stick "Report a bug, Request a feature" as a link on all of the pages. Then give the user a simple text field to type their comment into. If you want to go fancier, I think iminlikewithyou.com has a nice feedback mechanism. (The implication being that you could look at their site and steal the mechanism :) )