One thing I've heard a few times from people are that it would be good to have multiple states that the user can switch between with a press of a button (i.e. pressing 1 to look happy, 2 to look sad, 3 to look angry, etc). My only thought on that is it might require user-bindable keys to avoid interfering with the keybindings people use for other programs, so it could potentially be a bit of work to implement custom-bindable keys.