One minute you and your friends are hanging out at an awesome party, the next you're on the roof watching lower Manhattan erupt into flames. Bummer. Part homage to the original "Godzilla," part allegory (Sept. 11), the film uses shaky home-video footage to give you that "you are really here" feeling as panic ensues while a 200-foot-tall monster flattens the city. And props to anyone who can sit through the subway tunnel scenes without shrieking