Edison is a simple PC power management tool that can cut your PC's energy use, helping to save electricity, the environment, and maybe a worthwhile amount of cash.
At its core, the program offers little more than Windows own power management tools. It lets you decide how long your PC should be idle before turning off the display, powering down the hard drive or suspending your computer, but that's about it.
Edison does improve on Windows by allowing you to choose different settings for "Work Time" and "Non-Work Time", though. If you're more likely to leave your PC on at the weekend, say, then you're able to set shorter delays before turning off the display or hard drive, and these will apply to Saturday and Sunday alone.
Edison can even estimate the annual savings it'll bring you. This suggested that the default settings would save us £58.84 a year, equivalent to 490.33 kWh of energy or 303.15 kg of CO2. These are only estimates, but if they're close to being true then it may be a program worth trying.