I thought you *couldn't* do this reliably. When I look in %ENV there is a key called UNIQUE_ID which usually has a value like: OVN3hsdpVpAAAGiyLKs

But I thought that UNIQUE_ID changed with every request?
And IP tracking works right up to the point when you start dealing with AOL users or people with naughty proxy servers.

If there is a magical bouncing ball, does anyone know where to find it and track it? I would LOVE to stop fiddling with cookies.

update
I thought I would mention that you can stick a unique number into the URL line and track the user's identity in the $ENV{'QUERY_STRING'}. But that is visible to the user and just plain yucky looking : )
oakbox
"If what I'm saying doesn't make sense, that's because sense cannot be made, it's something that must be sensed"-J.S. Hall