Should I take the bus? Or have I been good enough to the earth that I can splurge on the car this morning? Carbon Hero, the brainchild of design student Andreas Zachariah, serves as your personal carbon calculator. Small enough to serve as your keychain, it monitors your transportation habits and calculates your personal impact on the environment. Download the data to your PC or cell phone (as shown), and get a glimpse into your personal transit habits. We might use this to see when we've been a bit too indulgent with the car on the weekends, and those with grueling commutes could make more educated decisions about how they get around town. -via Oh Gizmo!