This is about as geeky as it gets!
http://www.milkpaton.co.uk
Okay basically, give the above page a visit, and click the wee thing in the bottom right. Enter a name, then choose "Enable" or whatever it says.
Once you do this, you get to see everyone else who is viewing the site - by seeing where they have their mouse on screen!
Its easier to just try it, especially if a bunch of people are doing it at the same time.
I REALLY like this. I think on a bigger site - Im just testing it out now - this would really help visitors connect, give a sense of activity, and just make it seem alive.