Two Chat features that I think would be good:
1) Tabs on the chat, so when you are in a game lobby waiting for a game to start you can tab between the main lobby and the game lobby.
-- When lines appear the text in the tab would go bold or flash, when your name is mentioned, it would change to red or something and go bold or flash.
2) When someone mentions your name in a lobby the line of text is highlighted and a notification sound is played.