My eyes. I've been told alternately striking, and evil eyes. I've also been told that when I look at someone, it's like I'm staring into their soul. I guess they're right, because I've always been able to tell things about people.
It may not help that my voice can be quite deep when I want to it be.
I can imitate accents very well. I've spoken to British people (I'm from Canada), and they thought I was British.
I can also act well, mainly when I want people to do things for me, I can tell lies very well. People know this, and distrust me a little.
Also, pale. Quite pale.
My clothes also count, because all I wear are jeans, and either a golf shirt, dress shirt, or plain t-shirt. Never anything with a design on it.
And, I complain about the weather a lot, but that's a personality thing.
EDIT: I also usually do not show emotions in public, only when I'm among friends.