Don't think I have seen this one posted here, but rather than a heating pad
which can get too hot, and a heated washcloth which can lose heat quickly,
it you take some dry, uncooked rice and heat it for about 15-20 seconds in
the microwave in a ziplock bag (I leave the bag unzipped until I am done
heating) then wrap it in a washcloth, you have a heat source which will
hold the heat for two + hours, and when it cools will not feel cold (like
the washcloth will).  It is almost free, and readily available in most
houses (great if you are on vacation or visiting people).
 
-Anne
[Posted in FML issue 2539]