Having suffered a minor coronary after getting last month's electricity bill, I'm now training myself to turn off the lights as I leave a room. For each time I remember, I get a cookie. For each time I forget, I beat myself with a wooden coat-hanger. It's interesting that in the time since I started this I've put on only 3oz but have dislocated my shoulders on more than eight occasions. If only I had known about Sunlight Direct's innovative halogen/solar lighting, I could've saved myself several hospital visits.
When installed (by a custom lighting engineer, naturally), Sunlight Direct's halogens look like any other. What sets them apart, however, is the cool sunlight collector mounted on your roof, which gathers up the sun's glorious rays and funnels them down lengths of fibre optic cable, into a refractor inside the halogen lamp. That way, you don't have to turn the artificial lighting up as much, because you're using the natural light instead - only it's focused where you want it to be, not where the windows prescribe it.
Discovery Channel segment on the product
You don't have to remember to dim the lights, either; a microprocessor monitors the amount of sunlight coming through, and automatically increases or decreases the electricity to the halogens in order to maintain a steady overall light level. The manufacturers claim up to twenty times longer life for your bulbs, due to the lessened load, plus of course they're environmentally friendly because of their efficiency.
It's a price-on-application deal, which generally doesn't mean cheap, but if you're planning on lots of lighting in a new-build or renovation then it might work out cost effective in the long-term to look into offsetting your on-grid dependency with nature's freebie. Plus, if you're in the US, you can qualify for a 30% federal tax credit if you install in 2006 or 2007.