The cremation of the average male in Australia (less fat then the American male), during which the body is heated to 850 degrees Celsius (1,562°F ) for 90 minutes, produced more than 110 pounds of carbon dioxide. Hey, selling the carbon credit for your cremation could return enough cash for a proper plant me in the earth burial.
We decided that the suggestion to drill a hole in the ground and stick the "natural" body in feet first with a tree sapling as a marker is the way to go. This should take place with the leftover parts after the "donation my body to science" people are done.
Setting up a company to help people compost their loved ones may be a nice business opportunity for aging baby boomers. There will be some zoning and health code reform required before it is commercially viable but you might be able to get away with it in your own back yard if the neighbors don't complain (just like we to today with the kid's dead pets).
Check out the Yahoo!News article, Scientist says cremation should meet a timely death, on the subject.