This blog gives a great (short) post about the significance changing one light bulb (or all) in your house today can not only benefit the environment, but you. Take a quick peak and then go get a CFL and change a bulb! (Or, if you weren't planning on running errands today, maybe wait until your next big trip so you save some gas.) I've changed all but one of the normal-sized light bulbs in my house with CFLs (and the last one I just bought and haven't put in quite yet). Did you know that one CFL can save you about $30 in electricity costs during its lifetime? Now count how many light bulbs you have in your house and multiply that by 30. Nice number, isn't it?
And in case you forgot, I wrote a post here that gives you links to lots of interesting and useful information about CFLs.