This post for people who travel internationally. …
Gizmodo posted the best explanation I’ve ever seen.
Giz Explains: Why Every Country Has a Different F#$%ing Plug

… Is There Any Hope for the Future?
No. I talked to Gabriela Ehrlich, head of communications for the International Electrotechnical Commission, which is still doing its thing over in Switzerland, and the outlook isn’t great. “There are standards, and there is a plug that has been designed. The problem is, really, everyone’s invested in their own system. It’s difficult to get away from that.” …
Strangely, the article doesn’t address solutions.
Here’s what I’m using.

This adaptor “works” in about 150 countries. Sold by Fujifilm, it’s the main one available (greatly overpriced) in airports right now. Spend the extra couple of bucks for the one with a USB port if you frequently charge an iPod or other USB device.
In North America, I always carry one of these 3 prong to 2 prong adapters on my laptop cord. It’s amazing how many times it’s saved me in older buildings that only have 2 prong outlets.

Slightly dangerous, I understand you can no longer buy these in Canada. But God Bless the U.S.A., you can still get them there.