Everyone has a different theory on the best ways to be "green" and environment-friendly, but it's hard to know where to start until you know how energy-efficient you already are. It's fairly easy to figure out the carbon footprint of, say, your car, but what about smaller things like your computer or paper usage?

ECOBOT is a free, open source Adobe AIR application that watches your fuel, paper, and power consumption to help you determine where you're having the most negative impact on the environment and what you're doing right.

The idea to build an open source car isn't a new one, but you've got to give vehicle design company Riversimple credit for originality. The company plans to unveil its first car in London later this month, a small two-seater that weighs roughly 700 pounds. If you agree to lease one for 20 years (yes, 20), Riversimple will throw in the cost of fuel for the lifetime of the lease.

The team decided to release the car's designs under an open source license in order to speed up the time it takes to develop the vehicle while also driving down the cost of its components. There's an altruistic value to the idea as well.

Were you one of those people who turned the lights out and the power off for Earth Hour last month? Did you experience an excruciating sixty minutes of email/identi.ca/Facebook withdrawal? Userful has some good news (and a reward for your efforts) -- from now until Earth Day (April 22nd), it is giving away two-user licenses for its Userful Multiplier software.

So this time around, instead of turning the computer off, you can get the most out of its power consumption by sharing it with another user. While the Userful Multiplier software runs only on Linux, Userful is offering liveCDs bundled with the Multiplier software as part of this promotion, so those running other platforms can share the experience without making system changes.