There's a long list of films here spanning from the present to the earliest days of cinema, and all you have to do is check off whether you've actually watched them or not. At the end you click a button and your score is tabulated (I came out with 69.6%).
Knowing Monster, Satorical, and Wernda as I do -- I get the feeling that my score is easily beatable, but it's an interesting exercise in realizing that there are a bunch of films I've read about and know a lot about that I've actually never watched.
I will also caution you that some of the more modern choices that are on this list qualify as head-scratchers (In Bruges??) -- which makes the film nerd in me a little agitated that my score was somehow negatively affected by my choice not to watch Colin Farrel try to be funny.
But as with all lists, it's a subjective thing -- and being that it's all in the spirit of fun, it's not worth really freaking out about.