I'll be bringing American electronics with typical 2- and 3-prong plugs on a trip to Thailand, Laos, Cambodia, and Vietnam.
What do I need to buy to be able to use them?
an adapter plug - your US plug goes into the back of it, the front has the appropriate shaped prongs for the destination country. Get them at the airport as you depart. Our good friends over at Travelfish have some good advice on this issue:
http://www.travelfish.org/faq_answer.php?qID=13 about 5 years ago