Do you know about these bulbs? You should, and I'd be willing to guess that you have a few of them in your house. These are compact fluorescent lights, or CFL's, and up until recently they were supposedly the best bulbs you could use in lights in your house. I know it was only a few years ago that these were the best and most efficient bulbs around, but now is the time of they LED.
One of my favorite tech sites The Wirecutter has a great feature on LED bulbs, why you should use them, and what they believe to be the best bulb on the market right now. The article is very thorough and worth a read.
Since I trust The Wirecutter 100% and because I just moved into a new apartment and needed some efficient bulbs I decided to buy a bunch of these. One of the best things about LED bulbs over CFL's is that LED works better when you are doing dimming. It is my motto that "everything must be dimmable" and the CFL's just aren't cut out for it. In a dimmer setup hey flicker a lot, make noise, and don't turn on as fast. And considering these new Cree bulbs are supposed to be more efficient, I think we have a solid winner here.
Home Depot actually had a pretty interesting display setup when I went to buy these bulbs. They had a regular 60 watt incandescent build, a 60 watt CFL, and a Cree 60 watt LED bulb. Their respective power usage was 17.23, 4.33, and 3.46 watts per hour. Clearly when using CFL or LED over an older incandescent bulb, you are saving a lot of power, but the Cree is just more efficient overall.
No matter what brand bulb you choose, you'd be doing yourself and even the world a favor by replacing any old incandesenct bulbs you may have with LED's. If you want to get the Cree variety, which I highly recommend, you'll have to get them at Home Depot. They have an exclusive deal at the moment where you can get them in the 40 or 60 watt variety,
Go forth, purchase some LED's, set the mood with a dimmer, and save energy all at the same time!