Buy.com has the Sling Media SlingLink Turbo 4-Port power line networking adapter for $99.95. This includes two modules, a one-port bridge which connects your Ethernet network to the power line, and a 4-port switch which connects up to four Ethernet devices to the power line. This provides a high-speed (85Mbps) network in your home when you’re not able to run Ethernet cabling. And it is faster, and often more reliable, than 802.11g WiFi. Great for a Slingbox, but also for a TiVo, game console, Blu-ray deck, etc. The full MSRP is $149.99.
Disclaimer: I’m employed by Sling Media.