Thunderbird has a nice feature where you can right-click on a thread in a newsgroup or mail folder and mark an entire thread as read. It's essential if you read any high-volume newsgroups or mailing lists. When I switched to Evolution recently, I checked all the menus for something similar, but couldn't find it. But I happened on the solution when poking through a mailing list one day (and I forgot which one): <CTRL-H><CTRL-K> .

It's actually two separate commands: the first command selects all the messages in a thread, and the second marks them all as read. You can run each from the menu, but using the keyboard is much, much quicker. Score one for keyboard shortcuts!