The black character always dies, the dumb blonde girl always dies, the slutty chick always dies, the pothead or drunk always dies, the virgin always lives, any time a character gets naked for any reason (shower, swimming, sex, etc) they get brutally slaughtered, there's often a creepy little white girl or creepy little white boy, autistic children are always psychics, vampire women are bisexual, Gypsies are evil, cops are all incompetent jerks who never help you or believe your story, and cars never work when you need them to.
That's all I can think of right now.