Cellulosic Ethanol seems like the best overall bet for ethanol I have seen to date. I have heard that soft woods like willows and populars can be used as well. Woodlots that could be placed into a coppice culture would completely remove the need to plow and much of the fertilizer and pesticide issues that make corn ethanol such a problem.

Article from Wired here:
http://www.wiserearth.org/resource/view/a56c19e335bf6741a57b0663a5a710d7
Info here:
http://en.wikipedia.org/wiki/Cellulosic_ethanol

Another issue that I am very interested in is wood chip gasification. Was very big back in Northern Europe in WWI and FEMA even updated the process under the Clinton Administration to provide the technology for simple localized fuel production from locally availble resources. It is simple enough that a bunch of friends and I built a working model in a long weekend.

Info here:
http://www.gengas.nu/byggbes/index.shtml
http://www.green-trust.org/woodgas.htm

See our exploits here:
http://onestraw.wordpress.com/?s=gasifier

Hope this helps!