What is that thing in the lower right corner?

Its right next to the chat box with 4 colored balls and an arrow pointing to the tan one? :confused:

That selects the current default chat channel. Orange is Area chat, Green is Group Chat, I believe the one after that is for PvP and the blue one is for Clan chat. This way every time you hit Enter to type a message it will go to that channel every time instead of typing /clan or /group.

It indicates which chat channel you are in. Press X to select a channel.

That's the different chat channels you can communicate in.

if only clan chat would work :(

That is Trion's much "celebrated" chat system, a true highlight of the game to be sure....