Update: Newer, better options include the Fire TV Stick with Alexa Voice Remote | Streaming Media Player and the Roku Streaming Stick.
The Google Chromecast HDMI Streaming Media Player is a $35 digital media player that plugs directly into the HDMI port on your TV, tablet, laptop, or phone to stream online content from Netflix, YouTube, Hulu Plus, Pandora Radio, and many Google Play media apps.
Chromecast has become a strong competitor to the Apple TV and Roku as it enters the over-the-top television space.