Airport Express
If you spend a lot of time in hotel rooms tethered to a 3" blue Ethernet leash or racking up $9.95-a-day wireless charges, this little white box could be the handiest 7.58 ounces in your computer bag. Originally marketed as a device for extending the range of an existing Wi-Fi network or for beaming music from a computer to a home stereo system, Apple's Airport Express also functions as a wireless base station in its own right. Just plug that Ethernet cable into the box and the box into an unoccupied outlet. When you fire up your computer, the transmitter shows up, ready to be configured into your own private Wi-Fi domain. Share it with whoever is in the room with you or, if you don't enter a password, your neighbors down the hall.
List price: $99
—Philip Elmer-Dewitt