If you are at all concerned with analyzing user activity on your site, then you are probably already using a tool such as Google Analytics or Statcounter. These are two very good tools and they give a LOT of information. A new site called ClickTale however is pushing the envelope in this arena with some very interesting features. They give their users the ability to play back movies of users’ activity on their site, including clicks, hovering over links, scrolling, etc. This feature alone is worth taking a look at. You could really get into your visitors heads and see what they like about your site and what they don’t like.
There is an article on Mashable (ClickTale Launches Link Analytics: How Hot is Your Site?) covering ClickTale’s recent launch.