Blueline’s Power Cost Monitor, a device that hooks up to your meter, promises to save you money by providing up-to-the-minute data about your energy consumption and related costs.

Until recently, energy was something many people tended to pay for without thinking about it. We use it all the time but only pay for it once a month. Unlike gas, which we might buy daily, the infrequency of home energy billing compared to use makes it difficult for us to learn about our own consumption patterns and costs. For instance, you probably know about how much it costs to drive 20 miles, but how much do you spend running your dryer for two hours? Knowing those costs could help you make better choices, like setting up a clothesline to reduce dryer use or not turning on superfluous lights if it you knew that each cost you a buck per hour, for example.

That is what the Power Cost Monitor does. Once you hook it up (a task that's apparently somewhat complicated; see linked blog), it’ll tell you what your energy use costs you per hour. This knowledge can help you a) obsess over your energy use b) get paranoid about wasting energy or c) save you money and help the environment. Correct answer: c.