This person wrote a comment on Slashdot, which I felt I had to reply to. I liked the way my reply was worded, so I thought I'd copy it here and kill a few stoned birds...
"I estimate rather conservatively that my compact florescent (CF) bulbs will pay for themselves in less than 18 months"
Sorry to burst your bulb, but this is a really dangerous style of reasoning.
For example, there are a lot of ads at the bus shelters here in Ottawa talking about how ethanol and biodiesel "reduces" greenhouse gases.
I'm sorry, but when you burn any hydrocarbon there are more--not less--GHGs in the atmosphere as a result. Carpooling with one other person will reduce your emissions by 50%; teleworking or cycling one day per week will reduce by 20%.
Similarly, CF bulbs (yes, I do use them) don't "pay for themselves": you don't get paid to use them, they only cost less, when compared to an older, less efficient technology. Do you still hear people talk about the money that they save from not having to pay for lamp oil by using incandescents?
That's why I don't bother with those LED Christmas lights: sure they use less energy than the old kind, but I use no energy at all when I don't have any Christmas lights! (well, plus I have it in for Christmas; see username)
The advantage of performing a task with less energy (or at less cost, or with fewer pollutants) often distracts people from asking themselves if that task needs to be done at all, or as much.