Most people are now aware of the energy saving lightbulb. There are various types of bulb available, such as halogen, compact fluorescent and LED, which will fit most standard light fittings. Compact fluorescents are now available for dimmable fittings too. They also have a “mixed” reputation, as some technologies, and some manufacturers are better than others.
Compact fluorescents are often slow to reach their full brightness, and the “equivalent” wattage claimed is usually ambitious. For areas where the lights are on and off a lot, e.g. stairs and landings, they may be less suitable. For rooms where lights are left on for long periods, they generally work fine. Some people are concerned about their eventual disposal as they contain mercury.
The “next big thing” will be LED lights. They offer even greater energy savings, a 3.6W LED fitting can give off as much light as a 35W low voltage halogen, and they come on instantly, so fine for sporadic use. There are a limited range of fittings and they are quite expensive, but as they can last many years, maybe we should look at them as a capital expenditure, rather than a replaceable item. They will certainly pay for themselves.