Sharded secrets... you only have one part of a key or keys needed to decrypt some data so even extracting that from you by torture will not suffice. Of course this isn't always practical.
The trick is to ensure you are never near all the people who know the secret when there is the possibility of trouble. That makes kidnapping everyone harder.
Of course if you really worry about such things you shouldn't be trusting the other people you are working with either...
