I think, if the User List feature is implemeted, we can adapt it for showing the viewer list. I suggest you put a viewerlist button behind the subject or before the quote button of each post in the same line. After clicking on it, it pass the post_id to User List, then it display only part of the users.
As for Anonymous user, we can count by different IP address. As registered users, show their view count. [originally posted on jforum.net by andowson]
You showed up just in time for the waffles! And this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop