Yeah, I know, not much of a feature. Just thought I'd throw it out there. It's off by default, you can enable it on your settings page.

Also, for those who heavily use FO lists, I recently added a feature to put a green line in the thread list when the FO list changes. So if you reply to a message from one FO list, but only to your own FO list, it will show up with the line showing where the change occurred. I don't expect this to have a major effect either, but when it happens, it should be useful.