Though obvious to most, it never ceases to amaze me how many people show up to business meetings without a pen and paper. Even if you don't take any notes, at least be prepared. Having the proper tools shows professionalism, while showing up empty handed implies that the meeting is a waste of your time.
I alway carry a pen on me, even when I'm just stepping away from my desk for a momment, but I have OCD problems. My little black book is also great for taking quick notes.