Update: When I last reviewed this travel gadget, it was about 6 years ago. Recently mine broke so I started looking for another one. It was then that I realized that the one I was linking to on Amazon was no longer available. Fortunately, I found an alternate item - it is the same product, just with a different label. I still love it and just bought another one. The original review is below, with a few tweaks and updates. Enjoy!
I was in the UK last week, and got some "Ooh's and ahh's" over my latest Travel Light gadget: A Universal Plug Adapter. This is the second time I've used it, and I'm very pleased with it.
The APC adapter is a "McGyver" looking device that packs flat so it's easy to stow in your laptop bag. It can be reconfigured to fit just about any power plug combination you'll find in the world (input or output). In other words, it's great for any traveler - not just those from the USA.
Note that this device doesn't convert power, but it does make the plugs compatible. Since all of the devices I travel with (laptop, iPad, iPhone, Nintendo DS Lite, Kindle, etc.) have chargers that can handle 110v or 220v AC, all I need is a way to make the plug fit. This adapter fills the bill perfectly.
In the picture at right, you'll see what it looks like in its "default" mode, which is the most streamlined for travel (and can be used for central European, 2-pronged outlets).
By separating the two sections of the adapter and connecting it in different configurations, you can use it for other countries' adapters. For example, in the picture at left, you see the configuration I used last week, so I could plug into those big, honkin' UK dryer plug outlets.
Note that there are two prongs sticking out of the top in the photo -- have no fear, they aren't "hot" in this configuration, and have no current going through them when you plug this into an outlet.
I used to have a different kind of power adapter, but it was a bit thick and bulky for my tastes, so I moved to this new, lighter adapter. If you travel internationally and want to be prepared to power up in any country in which you may find yourself, then I highly recommend this Universal Plug Adapter.