I use a homemade alcohol stove all the time, unless I need to melt snow for water in which case a more powerful stove is needed. Alcohol stoves cannot be beat for their weight efficiency -- most stoves weigh just .3 oz and need just .6 oz of alcohol to boil 2 cups of water. Alcohol stoves rarely break and never clog up; they are much less expensive than mass-produced stoves too. Directions to make the stove that I use have been posted by Ryan Bozis (aka Major Slacker) at HikingHQ.net.
For other directions on how to make your own alcohol stove, or for lots of great information on different types of stoves, visit www.ZenStoves.com. To buy an alcohol stove, visit MiniBullDesign.com.
The only problem with the alcohol stove is that it's either on or off. If you insist on having a variable flame output, then I'd recommend a lightweight canister stove like the Vargo Jet-Ti Stove (2.7 oz). Compared to a white gas stove, canister stoves are: