Reading this Lifehacker Post about traveling with a laptop; ran into this very smart system/hack to prevent hotel guests from leaving the lights on and wasting energy…
“The one electricity issue that surprised me was this: At two of the three moderate to high-priced hotels I stayed at (between $26 and $80/night), the power was only on in your room when you were there. You’d have to place your room key in a slot to enable it. This is a pretty ingenious savings measure on the part of the hotel—electricity is expensive in Thailand, especially on the islands—but it means you can’t leave on the A/C, or charge your gadgets while you’re not in the room. A few nights I forgot to plug things in to charge while I slept, so the next day I had to haul around dead gadgets. Bummer.”
The post goes on with a tons of other useful tips. Well worth a skim.