The Negawatt iPhone app is exactly what you need to become a green homeowner. The application is intended to help users become more energy efficient in their homes. Giving advice about the way users light their homes, Negawatt keeps you energy conscious and wary of how much you're spending -- and saving.
The Negawatt iPhone app also delivers an overall summary in terms of dollars and energy consumed to keep you on the ball. A CO2 footprint statistic is also provided, letting users know how much of an impact they hopefully aren't leaving.