paypal me $50 and it'll offset your carbon for like 6 months.
what it *supposedly* does is go to conservation... funds restoring forests or updating power plants or some shens like that. it's a completely incalculable number but they use it to get donations from people who feel bad about their environmental impact. a more efficient use of the money would be updating your own home...
updating all your appliances and AC/furnace plus all your lightbulbs is the best way to reduce electricity. planting bushes/tree's properly are also huge in helping heating/cooling costs. to get off of natural gas, getting a heat pump is huge. if you don't have a smart thermostat (the ones that simply adjust heating/cooling temps based on the time of day) then you should slap yourself