nerdyH sends us to LinuxDevices for a description of a tiny Linux device called the Marvell SheevaPlug.
"A $100 Linux wall wart could do to servers what netbooks did to notebooks. With the Marvell SheevaPlug, you get a completely open (hardware and software) Linux server resembling a typical wall-wart power adapter, but running Linux on a 1.2GHz CPU, with 512MB of RAM, and 512MB of Flash. I/O includes USB 2.0, gigabit Ethernet, while expansion is provided via an SDIO slot. The power draw is a nightlight-like 5 Watts. Marvell says it plans to give Linux developers everything they need to deliver 'disruptive' services on the device."
The article links four products built on the SheevaPlug, none of them shipping quite yet. The development kit is available from Marvell.