The use case am considering is to do self testing on your site yourself, rather than depending on any third party, I plan to OpenSource it.
I am storing the mouse movement coordinates of the user in a javascript array which I plan to send to server every few seconds and save into DB.
Where I plan to aggregate the data and show final results.
What do you think?
http://websymphony.github.com/labs/trackerapp/
Currently tested on only Chrome.