YouTube: The Web's largest video-sharing site, is widely available on most set-top boxes and connected TVs for free. But YouTube navigation and search can be particularly laborious unless your remote is Internet-ready (keyboard, motion features, touchpad, and so forth). Also, some older YouTube client apps have problems playing high-definition videos, and in that case you might end up with a horribly pixelated, low-res video on your HDTV if you're not careful.
Sports: You may be able to stream the game you missed via an on-demand streaming app that keeps box scores, highlights, and sometimes the entire game. Pick your favorite mobile device, install the app, and you can catch sports whenever and wherever you want.
Other media apps: Plenty of the streaming media services you likely already use on your computer have apps available for your connected TV or set-top box--Napster, Pandora, and Slacker Radio for music, Flickr and Picasa for photos, and social media apps such as Facebook.
If you wonder what HDCP or a dozen other terms mean, here's a quick guide.