Basically, something to allow the user to put a server/host/IP on a list at the click of a button, preventing it from appearing in the users server list ever again (unless removed from the list of course).
The user could access that list in a GUI, or something of the sort, and remove/edit/add as they wish (maybe this could be implemented into the server Information in the RTB add-on).
We all know some servers do not have good hosts/admins or something you dislike, and although the answer is generally to "don't go to bad servers", this would be a way for people to fish them out for themselves permanently.
Whether if something like this is possible or not is beyond me, but I think it could be useful for some.
Also, this is not bashing v14's feature of allowing more players to host. This is something that might have been useful beforehand.