SuperCat Stove

There are many reasons why you might want a lightweight stove that's powerful enough to boil water.  I carry one on backpacking trips, but one would also be handy if the power goes out at your home (hurricane or other natural disaster).

Andrew Skurka has a page showing you how to make the awesomely simple and very efficient SuperCat stove, so called because you make it from a cat food can.  Seriously.  I can vouch for this design because it's the exact same stove I use when camping.

Check it out.