Let's face it, even when we recycle, we're nagged by a feeling that our actions, so small in the scheme of things, will do little to curb global warming. Enter the website Carbonrally, which aims to inject some competition into CO2 reduction. The site hosts weekly "challenges"-like replacing three household light bulbs with CFLs or topping off your tires-in which teams or individuals vie for prizes and "greener-than-thou" bragging rights. Two departments at Google recently battled in a Carbonrally face-off, while a high school in New Jersey started a Gossip Girl-esque commentary on the competition. The site's founder, Jason Karas, says the point is to get whole communities involved, by whatever means necessary: "For some it's getting together to support a cause. For others, it's a race."LEARN MOREcarbonrally.com