Envi Home Energy Monitor ($120) makes tracking home energy use fun and easy. Attaching the monitor to your electrical box allows you to receive real time information about how much energy your home is consuming.
The monitor has some really great features. The monitor itself is wireless and can typically be taken anywhere around the house. The monitor updates energy usage every six seconds, making it easy to tell which appliances are using the most energy in your home. These features alone make this a great buy, but the coolest thing about this monitor is that it can connect to Google Power Meter, an application that allows you to track your home's energy usage on the internet.