Here's a trick I've been using, thought I'd pass it on.
Invariably the first impression you're going to make with your interviewer is with your greeting, and a big part of this is your hand shake. However, with the cold weather now upon us, and you probably waiting in a drafty hallway, it can be hard to warm up your hands in the little time you have.
Pop a couple of these little hand warmers in your coat pockets and when it comes time for that all important hand shake, even on the coldest days, you'll have a warm friendly hand to greet them with, a nice smile to go along with it (because you know your little trick worked) and they will always remember you. "I can't put my finger on it, but he/she had such a nice hand shake."
I've handed some things to friends on really cold days and they'll say "HEY! Your hands are hot!"
(Hope that image is showing, it's there on the 'preview' and 'edit')