[rvdm]

Some interesting things could happen if you where to start collecting every user's visit with a timestamp.

For example, ip address + timestamp + even a rough geo ip location could reveal travel patterns of users simply visiting your site.

Let's say those travel patterns include visits to nations less friendly to the US and you just might find out some details about someone ( or at least a certain IP ) they really wouldn't want you to know.

All you need is a web server and a little bit of javascript.