In Japan they have these nifty little packets called kairo that keep your hands warm when you take it out of the plastic packaging. They look like a tea bag but slightly larger and they are disposable. They last for about 5 hours. I ordered some from jbox.com a year ago and they work great, but they are currently out of stock for the moment. They do have the cute hello kitty case I have here. This is a photo of the case below.
cutenippon 