Overview of other biofuels and where biodiesel fits in.
What are the other "biofuels" are people talking about?
The United States Department of Energy's
Fuel Data Center fuels page lists (click links for that site's information)
straight vegetable oil (SVO)
To use vegetable oil as a fuel in most vehicles, the engine must be modified to accommodate the oil's high viscosity. People do it, however, and it works. Willie Nelson's SVO page has some good introductory information about vegetable oil vehicles.