Wow, I'm really shocked that so many people don't use hot water bottles!
It's not just about warmth, you know: I like to hug mine (in a protective cloth covering) as I fall asleep. It's a teddy bear for grown ups.
Electric blankets: this is a subject that terrifies me. The danger of wetting the bed and electrocuting myself would make me so tense that I would wet the bed and electrocute myself.