An AP story on the wire today suggests LEDs will soon be a viable alternative to incandescent bulbs and compact fluorescents, too.
Incandescents and CF bulbs are of course the most widely available choices for most people's lighting needs, unless, I suppose, you count candles. Both have major drawbacks - inefficiency (while I was writing this post, I had a funny parenthetical - (Who hasn't used an incandescent light to warm a chick?)), aesthetically displeasing light, contributions to mercury pollution and climate change, that sort of thing.
As the story points out, LEDs aren't ready to take over as your garden-variety solution to home-lighting problems, but maybe in a few years, they will be.