Starting just last night, Facebook has started rolling out a new Trusted Contacts feature under your account security settings. Here, you can pick three to five folks who will have the power to help you when you lock yourself out of your account luck a dummy.
It's pretty unlikely that you'll get accidentally locked out of your account such that you're helpless to get yourself back in, but it's not inconceivable. When it happens, give one of your trusted buddies a bell, and they'll be able to get a code and instructions to get you access.
Since the trusted contacts setting just showed up on our computers, I went in and turned it on to see what would happen if, rather than simply getting yourself locked out by accident, your account was hacked.
I was relieved to learn that to turn the feature on or edit it from a computer that Facebook doesn't associate with your account, you've got to enter a password. That doesn't do you a lot of good if the hacker has your password, but it will prevent some people from changing your preferences, I guess.
As the post from Facebook's security team notes, you should only pick people you would trust with a key to you house because you're handing them a lot of power. Trust is a hard thing, but it'll be worth it when you're in a bind. [Facebook]