While at school, I found myself needing to remote desktop or SSH into my computer quite frequently. I would send MATLAB scripts to run while I was in class or working on something else. I needed to either leave my desktop running (sucking around 200W while idle) or find a way to turn it on remotely. Wake-on-LAN
(WoL) works quite well but requires a wired, Ethernet connection, and try as I might, I could not get Wake on Wireless LAN (WoWLAN) to work with my hardware.
The Electric Imp with a simple switch allows for a different kind of Wake on Wireless LAN as long as you have WiFi access and a USB port that always provides power (even when the computer is off). This instructable is fairly straightforward but assumes you are comfortable soldering and stripping wires.