My chat.php page updates my who's online page as "chat". I use the Who's online at the top of each page. So I set it up to tell how many people are in chat.
Then, because they will drop off the who's online list after 10 minutes, I made a little pop-up window that pops up behind the chat window. That little pop up refreshes every 9 minutes, thus keeping them showing as "in chat" until they close the window.
See
screen shot attached.
