Mine's got papers, mail, that type of stuff on it, but it's not so crowded with items! I have my printer on a different surface, but prefer to keep plenty of room by the keyboard/mousepad.
I like to move the keyboard around, especially if I'm playing FPS and want to have one hand on the numpad, and another on the mousepad. Also I like to move it to fit my joystick on the desk next to it (joystick is tucked away in a cubbyhole until needed, still plugged in though)