This is kind of what I had envisioned the plug-in would do. A company that builds a chat room and a plug-in to see who is chatting can't assume that the plug-in won't be queried multiple times by each user. I would have assumed that they would use the approach of writing the chat statistics to a static file on some timed basis to prevent overloading the server.
But I guess sometimes the direct (simple) approach is what is used without consideration for performance.

So basically, I would have to setup a separate page (probably PHP) that runs thier plug-in and writes the result to a text file. Then setup a cron job to access the page every minute (or whatever time period).
Then in index.php (forum home) I would add some code that extracts the value from the text file and displays the number of users in the chat room.

Would accessing a text file be less overhead than storing the value in the database?

I really appreciate the help you are giving. It seems that most chat rooms should include this functionality. I am pretty suprised that it is this difficult to determine which app to use and how to integrate it.

Thanks again.