This is the most fun you'll have all day (and likely well into the night). It's also sure to make you want to throw your laptop through a window because your brain is about to melt down and run out of your ears.
Empire Magazine, in honor of its 20th anniversary, has put together a painting that's basically a series of movie references -- 50 to be exact, all supposedly from the last 20 years. As you scan around and get each answer, the part of the painting that provides that specific clue darkens, and the game itself keeps track of your answers in case you want to stop and pick it up later (which you'll probably need to at some point). Some of the references are shockingly obvious; some are damn near impossible to figure out. You'll be amazed at the ones you get right off the bat that you know others are racking their brains over, and you'll no doubt face-palm yourself into a coma at the ones you missed and shouldn't have.
For the record, I managed to get 47 right before hitting the wall. A few message boards have the answers but I seriously recommend trying to go as far as you possibly can without resorting to that.
Oh yeah, and I'll give you one clue: At least one of the movie references isn't technically from the last 20 years. They sort of cheated by counting a recent independent foreign film that happens to go by the same name as a more famous film from the 1970s.
Empire Online: Cryptic Canvas