Have you tried the bbPress forums?
@markaduffy – There was a bbPress plugin on the stand-alone side of things at one point, but I believe it hasn’t been updated in some time. I have a thought about how to do this in bbPress 2.0, but it would most likely not be persistent, and rather based off the last time a user visited the site.
@JohnJamesJacoby , I’ve noticed a lot of people wanting unread post highlighting. I would also really like the functionality.
I’d like to hire you to develop it. Are you interested?
Msg me here or email directly at kenny@fittedwebdesign.com. Thanks!
There’s a new plugin that has just been released that allows you to highlight unread bbPress forum topics
https://wordpress.org/extend/plugins/bbpress-mark-as-read/