I have a gadget sent from Japan called a kotatsu (search for kotatsu on wikipedia and you'll find an article about it). It's a table with a quilt over the frame and the leave set over that. Under the quilt there's a heater. And there's another padded quilt underneath to sit on.

It's incredibly warm - somehow, sitting under this, with your bottom half warmed, keeps all of you completely warm.

Only trouble is that I have to use a transformer to plug the heater into - I haven't got one that works for 220-240 volts, and don't know if you can get such a thing. So I'll often just put a hot water bottle in underneath and keep my tootsies on that.

There's a guy selling them on eBay, not too dear, sends them from Japan.