The first movie that comes to mind when thinking of a fantastic movie that nobody I know has heard about (except through me) is The Infidel. (I'd link to IMDB but I don't have enough posts to be allowed to yet.) The short summary is that it's a comedy about Mahmud Nasir (Omid Djalili), a mildly anti-semitic British Muslim man who learns that he was actually adopted–and his birth parents were Jewish. When the Rabbi at his birth father's old age home won't let him in for fear the shock of having a Muslim son would kill him, Mahmud turns to his neighbor, a Jewish cab driver (Richard Schiff, best known for playing Toby in the West Wing), for lessons on how to appear Jewish. At the same time, his son announces his engagement to the daughter of a prominent, ultra-conservative Islamic cleric, and begs his father to act more devoutly Muslim. Hilarity ensues (and both Omid Djalili and Richard Schiff are fantastic in this).