Lighting is a pet peeve for me - I nearly got fired from my first real job for secretly removing all the fluorescent lights from above my desk. So it's been hard to be a fan of LEDs although they are superior to incandescents (and to CFLs) in efficiency. When it comes to Christmas tree lights, our household will forgo strings of lights altogether (though nixing the tree met fierce opposition). We will instead revert to the ancient Euro-tradition of having a few (a few!) clip-on parafin-free stearin candles for atmosphere, only lit during the scant time we'll spend around the tree.
But for those with big trees and/or the need for indoor and outdoor holiday lighting, it was a pleasant surprise to discover that the stark white of LED light strings is not too bad on a tree and can be make an appreciable difference - ok, about the price of a couple of lattés - in energy savings over the course of the month or so they are used. The Swedish Energy Department actually did a comparative study of the energy usage of 12 different brands of strings (here) of lights, most of them only available locally, but some, especially the Glänsa Lysa, stocked at local IKEAs. And it's not too late to get LEDs for this holiday! Burning LEDs for the entire holiday season can cost only pennies, according to Appalachian Power, though the purchase price is higher than incandescents. And at least one source, HolidayLEDs, will still (through today) take orders for the holidays - white or multi-colored strings. And they'll recycle old incandescent strings, a wonderful plus. Via ::HolidayLEDs