I actually learn a shit load from television. But I only really watch it during semester breaks. Pawn Stars teaches me about haggling and why certain things will have more economical value over other things.
American Pickers teaches me a little about the psychology of those that hoard and also why and how certain items can be so valuable.
Science channel taught me about the latest theory on supernovas, which shows good interpretive evidence toward the beginning of the universe starting out as one massive sun among other things. I also learned a lot about the history of Nasa and how they have come to understand the search for other life in the universe (I hope we find life on Europa; that would be neat).
South Park keeps me updated on popular culture.
The law and forensics shows sometimes teach me about...well law and forensics. I feel like I've gotten a better understanding of how a defense attorney operates and thinks in a court room just from these shows.
Syfy teaches me about what not to do if making a movie, especially made-for-tv movies.
Sometimes movies can give me a particular understanding of how someone like an arms dealer could rationalize and come to understand what they do for a living.
Homebuilding shows teach me about contractor scams and how to fix and maintain a house without having to hire someone else to do it.
And believe it or not, sometimes when I visit my mom she will watch design shows and I have learned a bit about different types of ways to style a home with furniture and such (which is actually pretty interesting to see things get completely renovated and why and how they do it).
