We've got a house guest staying with us for the next three weeks, which necessitated moving Lisa's desk and computer out of the home office and replacing it with a guest bed. We set up Lisa's desk and computer in our bedroom for now, and that immediately lead to the obvious question: how do we connect Lisa's computer to our home network? Her machine is old enough that it doesn't have wi-fi, so connecting to our wi-fi wasn't viable. I didn't want to have to run ethernet cable under the house and drill holes in the bedroom wall. The solution: Netgear's Powerline Ethernet Adapters, purchased from Amazon.
These adapters are pretty slick: you plug one in to a wall socket near your existing LAN and connect an ethernet cable. Then plug the second into a wall socket near where you want to extend the network and connect another ethernet cable. In our case, I ran this cable into a 4-port bridge so I could connect both Lisa's computer and our Vonage adapter. Once the adapters recognize each other, you push the little security button on each to generate a private encryption key, at which point the signal on the 60 Hz AC carrier is encrypted (the signal can cross breaker boxes but not transformers).
The other cool thing about these adapters is that they act as bridges rather than switches, so everthing stays on the same subnet and can see each other (i.e., no double NAT problems).
Pretty cool.