Global Timer

I'm in need of a "global" type timer that will allow me to basically run a clock the entire time someone is on my site, no matter what pages they go to.

I've played around with the timer available for forms but I didn't see a way to make it continue to run after someone left that page.

The effect I'm attempting to create is for a timer to start whenever someone hits my site, then every X minutes an event will trigger. This event should happen no matter where they are on the site.

I've read a couple articles on timers but to be honest I'm fairly new to VB and I didn't know if I really needed to learn about 'threading' etc, to get a timer to work.

Links to code or articles would be very appreciated.

Thannks

Forgot to put that I'm running .Net 3.5

Have them log in, and you can track that. Much easier. Otherwise, the IIS logs should give IP addresses