This document outlines a vision for “green computing for a clean tomorrow” [Feng06]. The first piece of the vision is a bit pedestrian – holistic energy-efficient computing “in a box” – but serves as a foundation to a more audacious (tongue-in-cheek) vision of holistic energy-efficient computing “in a world.” As recently noted by IDC in an IBM presentation at the Gartner Data Center Summit, December 2006, the annual spending for power and cooling would match the annual budget for new server spending in 2007, as shown in the figure below. In addition to cost, energy-efficient (power- aware) computing can enhance the reliability and availability of ever-increasingly dense computing systems, such as blades; it can also provide additional computational headroom when an institution has reached the limits of its power and cooling infrastructure, particularly when the infrastructure cannot be expanded any further [Feng08].