This is excellent - thanks very much.
Do you know if there is any way to produce a timestamp of when the user closes JMP?
If you install your tracking as an add-in, you can have an exit script. See page 526 of the scripting manual, "Specify Start-up and Exit Scripts (Optional)".
One caution when using a shared table for tracking - namely, user contention when 2 users are trying to open the file. More specifically, user1 has it open - then user2 starts up and tries to open it. A couple of ways to address this:
I've also seen user tracking done by borrowing methods of advertisers on the Internet - namely, web beacons. You could use the web() to open a web page.
I don't know of a way to do that, but Its not something I've tried to get at either.