It goes without saying that a papal conclave is about as anti-democratic a deliberative body as you can get, but certain aspects of Universi Dominici Gregis (John Paul's Rules of Conclave) do make sense: limiting the voting age, requiring a two-thirds supermajority, and enforcing strict internal ethical constraints.
I'd love to see other decision-making bodies like the U.S. Congress, the Supreme Court, and corporate and nonprofit boards hold themselves to the same standards.