Power of attorney for health care decisions. Password from bank to allow a wire transfer(this cannot be done over the phone unless you have made prior arrangements with your bank and they have given you a password). Drug prescriptions and contact info for all of your doctors. Emergency ontact info for a relative or friend that can make decisions about any personal items that may come up where neither of you are able to make those decisions.
These are just some of the things you should be prepared for and hopefully you will never need.