... perhaps using Power-Over-Ethernet
http://en.wikipedia.org/wiki/Power_over_Ethernet
...
The simplest method (but not, of course, the cheapest or cleverest) to get Open EEG over Ethernet or wireless is to plug it into a standard PC or laptop, and use the standard Ethernet or wireless interface in the PC.
http://gumstix.com/
has some interesting Wifi and Bluetooth devices.