To start tracking traffic to your docs:
1. Go to your Docs list and click 'Settings'.
2. In the 'Track published documents section', do the following three things:
a. Check the box that says 'Track visits to my Google Documents using Google Analytics.'
c. Finally, to find this tracking information, 'sign in' to Google Analytics. Click 'View reports' to see visitor stats for your published docs.
Note: This feature isn't currently available for spreadsheets, presentations, and Google Apps users.