The smartiepants at Xerox have recently invented *self-erasable paper* that fades to white after 24 hours. The invention "came from developing compounds that change color when they absorb a certain wavelength of light but then will gradually disappear." Hmmm... could be fun, or disastrous. Either way, I think the trees will dig it as the paper is reusable again.
But my advice from hereonin: wait more than 24 hours before signing any important documents!!