UP - Pressing up will step backwards through the move list and show you the previous position.
DOWN - Pressing down will step forward through the move list and show you the next board position.
ENTER - Pressing Enter will always bring up the Console cursor so you can enter text. Pressing Enter again will remove it and send anything you typed in between.
PAGE UP and PAGE DOWN - Pressing these keys will scroll the Console up and down.
SHIFT + UP and SHIFT + DOWN - These will scroll through the history of what you've typed previously. Very handy for repeating commands.
ALT + C - This will begin a reply to the last channel who sent you a tell.
ALT + K - This will begin a kibitz, which can be heard by everyone observing a match, including the players.
ALT + R - This will begin a reply to the last person who sent you a private tell.
ALT + W - This will begin a whisper, which can be heard by everyone observing the current match, but not by the players of that match.