I have always used the site getsatisfaction to use on my site. But I fell in love with wordpress and i'm using it instead. However, I can't add the feedback page code to the post in wordpress for it to show up on my contact page. (You can see the widget here http://getsatisfaction.com/widgets) It's great for keeping track of frequently asked questions or problems.
I've considered putting it the sidebar, but it's too wide of course so it'll get cut off.