I live in a cave.
Or, at least it seems that way at times. All the bulbs are 60-watt, and it's so dark in my kitchen that I usually have to have the stove light on as well just to see what I'm doing.
Well, I had a few burned out bulbs, and when I went to purchase replacements, I decided to start switching over to CFLs. And since I was switching to CFLs, I also opted to increase from 60-watt to 100-watt (equivalent brightness). So, not-quite-twice the brightness for just over a third the electrical cost.
Oh. My. Science.
It's so much brighter in my apartment, it's hard to describe. I no longer feel like I'm living in a cave. It's like stepping out into sunshine. I should have done this months ago.
An interesting side effect is that it is making me more aware of when I turn on the lights. See, if you turn on a CFL, you should leave it on for at least half an hour (which is why I don't use CFLs in the bathroom), otherwise you drastically shorten its lifespan. So now I am more aware of when I turn on the hallway light, for example. Because if I'm going to leave it on for 30+ minutes, I better be sure I need it. If it's a momentary need, I'll probably just leave it off and do without.