I don't think this option is currently possible, but here's what I was thinking:
When you bookmark webpages in most browsers you can name them what you want... I don't necessarily want to rename the threads in my bookmarks, but I *would* love to be able to add "tags" to them, i.e. "great Thai place, San Francisco" if someone mentioned in passing a great place they ate that I want to try, but the thread as a whole is like "places to eat before the theatre" from the SFBA board.
Just a passing thought that would be neat to see :)