It is the eternal question: How many users are connected to my IIS web site? A little poking, and I found that I could answer that question Performance Monitor.
First, click on the Add button (the “+” sign, highlighted in green). That will display the “Add Counters” window.
From the “Performance object” drop down list, select “Web Service”. This will change the list of counters on the list on the lower left. Select “Current Anonymous Users” and / or “Current NonAnonymous Users”, depending on what you want to track.
If you highlight the counter you wish to track. Look at the “Last” to see the latest count.
I’m certainly open to better ways of doing it, but it worked for me.