[numberonepal]

Check out what these guys are doing. They're making the bio-diesel in a washing machine with glycerine.

I've also read that mustard greens have the best concentrations of oil. A pretty significant difference from soy IIRC.

[SWake]

I've been reading up on this for the past week or so. Here's a chart that lists the amount of oil that can be produced from one acre of various crops:

http://journeytoforever.org/biodiesel_yield.html