Seeing what users are viewing

[eluser]dallen33[/eluser]
I'm using ion_auth and I'm wondering if there's an easy way to somehow see what pages users are on. For instance, if I'm viewing a page like http://localhost/insertion/112, I would like to know if another user is looking at it. So, via AJAX perhaps, a notification could come up and show the user. What's the best way to go about this?