It's the beginning of another summer full of sequels. This week "The Hangover III," "Fast & Furious 6," and "Before Midnight" all open. But coming soon is another Superman movie, and Hugh Jackman is once again playing Wolverine. Meanwhile, "Pirates of the Caribbean" is working on its fifth installment.
When should a movie franchise just call it quits? Which movie sequels are your favorites? Which ones didn't work at all? What makes a good sequel?