I think you can get some TV series like Friends, King of the Queens, Simpsons, Family guy. All those series you can learn a lot about the American culture. I remember back then, watching an episode of Friends when someone asked for quarter coins for laundry. I didn’t get the joke but now I know most people need quarters for the laundry.
Also, if you could read something about the history of the English language it would be interesting for your students and for yourself. Someone might ask you things like “from where the English came from?”
Or yet, “why the spelling of English is so different from the pronunciation?” There’s a book called “Inventing English” by Seth Lerer. He also has a series of DVDs called “The history of English language” you can find at Teaching Company website. I bought those DVDs and those are great!
Last but not least, there’s a dictionary called, “Dictionary of English language and culture” it has some info about dates and a bit of history.
That’s all. I hope this has been informative for you.