But with the hotels in Kyoto, Okayama and Hiroshima, we had cabled internet in the room. Good enough for the laptop, but not practical for the telephones. We survived fine without wifi, but it did cost me a few Wordfeud games because I couldn't connect for four days in Kyoto. And time on the laptop was at a premium...
So I bought a travel wifi router: an Edimax BR-6258n. It's a really small device: about a third of the size of my telephone, though thicker because it has to fit two UTP sockets. One socket is for the WAN, and one socket allows you to loop de wired internet through to the laptop -- handy for uploading movies, which is faster and more reliable through cable. The router is even powered by USB, so while you do get an adapter in the box, there is no pressing need for another adapter when using this. And the advantage of that is that the router shuts down when you power down the laptop -- so when you leave your room, nobody is going around using your wifi connection. It has all the features you'd expect from a wifi router, so I set an SSID and a WEP2 key for it, through a handy web interface.
I don't know what the range of the thing is. Apparently it's not up to par with the larger routers with external antennas, but there is no need for that: it has to cover a hotel room, not a soccer stadium.
I'm pretty pleased with this. I look forward to using it in the future!