Trackr is a very simple, lightweight (well, if you’re already using jQuery) user interaction tracker. It’s not particularly robust and is only in a fairly simple form right now.
The back end is written in PHP using MySQL for storage, but could easily be implemented in other languages.
To log data, you simply add a call to Trackr.init() to the page load event, passing the desired options as the only parameter to the function.
There are a variety of options that can be specified and for more information please see the test page.
You can get it here (includes jQuery 1.3.2).