"The idea driving this project is to turn any standard, off-the-shelf router into a Power Over Ethernet (PoE)-capable unit without buying any adapters or additional hardware.
PoE is somthing fairly common in many business/office spaces. For example, many wireless access points in office buildings and universities use the technology so they don't have to run a power receptacle to wireless access points. For this instructable though, we're going to use PoE in a residential setting. Even the big router companies are starting to sell these adaptors to consumers like this Linksys WAPPOE12. But I think it costs way too much and is kinda bulky. If you're into the DIY bulky thing though/have a need for an external PoE injector, you could try this option..."