Graph TV, an interactive application that visualizes TV show ratings. It was designed by Kevin Wu (website), a software engineer at Academia.edu. It's a joy to explore. See Game of Thrones above. The highest-rated episode by far is The Rains of Castamere (season 3, episode 9) for reasons that will be obvious to any fan. Please, if you have not watched it already, don't Google it up or you'll be very angry at me.
See how erratic Lost's ratings are:
The West Wing, a favorite of mine:
The Sopranos, which I also love:
And House of Cards, which I'm enjoying these days: