The Bios Urn, a completely biodegradable urn that contains a single tree seed. When planted, the tree seed is nourished by and absorbs the nutrients from the ashes. The urn itself is made from coconut shell and contains compacted peat and cellulose. The ashes are mixed with this, and the seed placed inside. You can even choose which type of tree you’d like to grow! So which would you prefer; leaving behind a tree or a tombstone?
Source: I fucking love science.
Beyond the obvious science-fiction links here, this is some great story material. I can imagine a story about karma, reincarnation and redemption.
A miserly scrooge who died alone in the world, was cremated and his ashes were stored in a biodegradable urn, forgotten by the world. A gardener, mistaking the urn as a germinating seedling, planted the urn into the garden of a orphanage. There the scrooge began life anew as a mighty apple tree.
As he grew with the children, watching them play, enjoy the fruits on his branches and sit upon his sturdy boughs, he finally understood that life was never about what you have, but what you gave. And giving made him happy. It was then, when he was but a tree with only apples to give, that he finally realised what it meant to be human.