Except for energy upgrades, of course the most environmentally friendly choice is to simply maintain your property as is. But if you are set on doing something, here are some good resources.
Marin County Green Bldg/Biz Programs
BuildItGreen.org
Straw Bale Construction
Considering bamboo flooring? Things to know.

Construction waste, recycling and salvage centers:
California Materials Exchange
Ohmega Salvage, Berkeley
Heritage Salvage, Sonoma County
Urban Ore, Berkeley