LinuxDevices.com features one of the smallest Linux computers available in the market today. Dubbed as Linutop PC, this 433Mhz AMD Geode LX700@0.8W powered computer comes with 256MB of RAM and 1GB of storage via a USB thumbdrive. Measuring at 9.3 x 2.7 x 15 cm, the Parisian startup's Xubuntu-powered computer weigh a mere 280 grams – if that is not small, then I do not know what is. :) Linutop has four USB 2 ports, audio and video port and a 10/100Mbps Ethernet card. WiFi can be added via the USB, which you have plenty. What is even better is it's now available for approximately US$380.
Now, think of the endless possible use of this device – portable web-server, firewall/proxy server, desktop, mail client, etc. Personally, I can use this is as a File server connecting several USB external hard disk drives. :) At 6 watts, that will save me a lot for operating this little critter.