By now you've probably heard of The Best Exotic Marigold Hotel, the British retirees in India movie starring Judi Dench and Maggie Smith (both 77), Bill Nighy and Tom Wilkinson. What you may not know is that the film, which cost about $10 million to make, has ticket sales approaching $100 million since opening earlier this month. Turns out that when you make movies that give talented older actors something to work with, you'll attract older audiences.