I had to augment my home network with an Ethernet over Power solution. My Apple TV was just getting a crummy wifi connection compared to everything else. So I got this thing that runs ethernet over a power line, plugged it it, and it Just Worked. Pretty happy with it.
It potentially exposes your wired net to your neighbors...
Note that some ISP's have delivered broadband over electric. (Read about it in Wired and in Datamation back in 1998.)