I have a D-Link powerline adapter with WiFi at the remote end. It works very, very well and I get full speed, for about 10 Minutes. Then it stalls, probably getting too hot.
Conclusion, Powerline is really good, but stay away from D-Link.
What is Powerline? It's sending data through the 220V net in your place. It works best (only?) when both power sockets are on the same circuit.