Those wacky DIY nutters over at Make have a bit devoted to making your own biofuel, including a link to an article about crafting your own homebrew biodiesel, starting small and then working your way up to moderate-scale backyard capacity. Hey, you've gotta do something with all those garden scraps, no? Now we just need a diesel lawn tractor.
How to Grow Your Own Oil [MAKE]
American Apparel Biodieseling its Employees [Internal]