Pulled from another forum with the same question.
"I use powerline network adapters to connect my detached garage that's about 50 or 60 feet from my house. The garage is on a sub-panel and the outlet that the source device is connected to is about 15 feet from the main panel.
They're made my Netgear - AV500 is the model.
I've not done any speed tests so far, since my goal was to get my Airport Express network access so I can stream music out in the garage / back yard. It's done very well in that regard so far.
I'll get some tests ran tonight and will post back.
EDIT: Ran a single speed test from the garage. Managed to get 23Mbps down / 19Mbps up. So yeah, not blazing fast, but fast enough for streaming music.
"