We are a geeky household, so we have a Mac Mini hooked up to our TV as an HDMI input. We have Hulu Plus and Netflix. Hulu does not have shows from CBS, CW, or the more popular cable channels like Discover, TNT, and USA. It does have the other major networks, SyFy, and some web programming like Keifer Sutherland's new series.
We also use a program/device on the computer called EyeTV, from elgato.com. This turns your computer into a TV receiver, so you can get the over-the-air TV on your computer. It also has a DVR capacity, so you can tape those shows just like a DVR (skipping the commercials), and you can watch on your iPod, etc. as well as the TV.
We also watch a lot of podcasts: there is a great Sesame Street one, that has a 5 minute show for each letter of the alphabet, and a Dragonfly TV one that is a great little 10 minute science show for older kids. For the grown-ups, there are TED talks, a local feed from the weather channel, and the national nightly news shows are available the next day.