Google's Chromecast HDMI streaming dongle just got a nice optional upgrade in the form of an official Ethernet adapter. As with any wireless device, the Chromecast's performance depends on the Wi-Fi signal quality in the spot where you have your TV. A bad or intermittent signal can turn the whole streaming experience from "this is great!" to "why won't this work?!"
To use this adapter, you just plug in an Ethernet cable from your switch or router, and run an included USB cable to the Chromecast itself. The Ethernet adapter will then feed both data and power to the dongle over USB. Ethernet connectivity is limited to 10/100Mbps speeds, but that should suffice for even the highest-definition video streams available today.
The Ethernet adapter is a mere $15 on the Google Store, so if Wi-Fi isn't cutting it for your Chromecast, at least the solution is inexpensive.