One Lightbulb at a A Time

At the UK's The Guardian, you can make a weekly pledge about relatively simple things you can do to reduce your carbon footprint.

Ideas that individuals can adopt right now, without investing in any household supplies or hardware: stop buying farmed flowers, stop using bottled water (refill the last bottle you bought at the water fountain until you get around to buying a Sigg), eat less meat, re-use plastic bags.

At the next level: replace one short-haul flight with a train journey, get a low-flow shower head, compost kitchen and garden waste.

The site will give you a little graph showing how much carbon you're saving with each pledge; it ought to be satisfying to watch the little green bar grow.