Get tivo and set to only allow kids to watch shows that you specifically allow. All other tv can be password protected. Works well for our family with young kids. The only crap left is the commercials (which can be plenty crappy).
When my kids find a show they like, I buy it on DVD, that way they can watch it whenever they want, and I don't have to deal with all the other self-promotion crap.
Right now they are on a High School Musical kick LOL. Thank Heavens they can shut their door, because if I have to hear that movie or its soundtrack one more time, I may go insane.