As a reminder, these kinds of applications record a user's browsing session, so that every glide of the mouse is captured. You can see when a user pauses and looks at an area of the screen for a while, and then starts scrolling up or down again, etc. It's exactly as though you were standing over your user's shoulder watching the cursor move and the web page scroll up and down. In addition, you can watch as users fill out a form on your site and get great info on your form's usability that way.
So, without further ado, the 3 competing User Browser Session Recording Apps:
RobotReplay - Free
TapeFailure - $8 - $98/month (You do get one week free to test the service, at which time you can stop or purchase a plan).
ClickTale - Free - $99/month
The paid versions generally allow you to record more sessions (more users), and get some advanced features as well. Because all three offer some form of free version, there's no harm in trying any of them.
Between normal web stats, heatmaps, and recorded browser sessions, there should be no excuse for not having a complete understanding of what your site can do better, both for your user and for your bottom line.