Not the television I like to watch, which would scar my children for life if they joined me. The kind of television that can lead to learning and "Wow, Mom! You're going to let us watch TV?" Well, maybe.
PBS has a lot of videos on-line. They have a lot of full episodes of NOVA. The page is broken down into categories like Earth, Nature, Physics and Math, and Space. Many of the videos seem interesting.
I'm looking forward to watching a few with or without my kids. Please remember to take the context of your child's knowledge into account. Basically, that's a warning that political views in particular will operate on assumed premises that many kids won't even understand enough to question. Politics, in particular, is a very abstract field that requires a lot of living, reading, and learning of human action and history to even begin to grasp.
I found out about the free shows on PBS from a local homeschooling support internet group.