That is what organizers for Earth Day Tokyo 2006 are asking volunteers, for which they'll pay a small amount. The organizers will then create biodiesel from the oil and use the resulting fuel to power the lighting, televisions, speakers, and other equipment for the various planned activities which to be held in Yoyogi Park. Besides the equipment, the fuel will also be used to power a special bus that will be touring the area.
The organizers have been accepting vegetable oil since the beginning of the month. More details, including drop off locations and "Earth Day Money" can be found at the link.
[Source: The Daily Yomiuri]