My Brother got me interested in alcohol stoves on a backpacking trip to do some some alpine lakes fishing last summer. The stove at the link Cowpokey posted is excellent; hot and boils quickly, pretty efficient, easy to make, and easy to recover unused fuel from. There are many other good, simple, and cheap to make designs too and I've now made several. A good place to check out is
Zen Stoves.
I currently have a simple but hot burning Super Cat low pressure side burner made from a 35₵ 3 oz can of cat food and a paper hole punch that is good for boiling a pint of water in about 5 minutes to make a dehydrated freezer bag meal and a hot drink, and a more complex small carbon felt wick top burner with a metered remote fuel supply that burns a bit cooler and is ideal for dry baking that cost about $8 to make, in a compact lightweight cooking/baking kit.