/worldchat on /worldchat off
In my opinion, a very useful tool to help get people out of Ul'Dah. As well as find groups.
You could even have a 30 second delay where you can't send another message in that channel to prevent spam. This way people don't flood or annoy the channel and it can remain relevant.
I feel this should be a separate channel with it's own text command to toggle it on and off. We don't have room for a separate 3rd window for this purpose. For me personally I might ignore it more often, if I had to go to the Configuration to enable/disable the filter.