What's the central point of failure for my 1Password vault?
It's stored on four of my devices. It's stored on Dropbox as well, but a compromise of Dropbox won't give the attacker anything because it uses secure crypto and I have a strong master password.
Share your master password with your friends. You can make it so that, say, 20 out of your 50 friends are required to piece together the master password.
