Leaving aside the argument about whether anyone needs a microwave or not, here is an option for those who do choose to have one. I saw an ad in PC World for the i Cube microwave, about a cubic foot in size (10.5" x 12" x 10"). No price was given but one web site lists it as about $130. It is 110 volt which means having a suitable inverter but the main reason for the high price of the "12 volt" one is because it has a built in inverter and I'd rather choose my own and use it for more than a microwave, if I go this route.
I didn't spend much time looking for independent reviews and I suspect it hasn't been out there long enough to have much consumer experience. I see it doesn't have a turntable which is a major drawback on a microwave, at least for anything more than a cup of water. It apparently has cooked a package of popcorn which is a good sign but there was no analysis of the burned kernels to old maids ratio.
The inventor needed to have hot wash towels in his bathroom so he made this microwave. I suspect he isn't a boater.
Here is the link for a detailed description:
http://the-gadgeteer.com/2008/03/19/iwa ... microwave/
More:
http://www.cleveland.com/brightideas/in ... ke_mi.html
The article says it was being marketed by Sharper Image which is now in bankruptcy (I doubt there is a connection) but i Cube does have a full page color ad in December's PC World (page 69) so I assume they are still in business. They list their web site:
www.iwavecube.com.
For the record, I have no connection to the company and had never heard of them until I saw the ad.
A cheaper option: Has anyone used one of those little "coil" heaters I had in college in the '60s to make hot water for my instant soup? I don't see them in the stores anymore but I have to believe they exist somewhere. I did see a 12 volt plug in version for $10 at a truck stop. How well will that work for heating water; the primary purpose of a quick and easy heater for me? I understand that watts converts directly to BTUs (or calories if you are metric) and I know what can be put through a "cigarette lighter" is pretty limited. The advantage to microwave heating is efficiency--little heat is wasted; no pot or cook top needs heating as well. However, an electric heating element directly immersed in water should be about as efficient as one could get as well without the cost, size, and complexity of a microwave.
The truck stop also sold a small water pot with the 12 volt heating element already built in. I had to rush out, my wife wasn't as keen as me about spending time in a truck stop retail establishment, so I didn't see how many watts these items were and they didn't make it readily clear.
Experience?