If I use a wood stove, it's a ZZip (http://www.zzstove.com/). It's heavier (17 oz.) than some, and not free but it burns like a forge. I've gotten flames a foot high out of mine and boiled water faster than my range at home. Charcoal, dung--it all burns under forced air and the ZZip will eat wet wood if that's all you've got.

If, however, you like to tinker, there are a ton of DIY stoves here:
http://zenstoves.net/Links.htm