Most accounts you set up these days with banks, email, credit cards, PayPal, etc. allow you (or force you) to create security questions in the event you forget your password and need to reset it. You know them; they are things like, “What was the name of your first pet,” or, “What was the model of your first car.” The variations are endless, but they all satisfy the condition of “something you know.”
Normally, these should be something that only YOU know, but you can easily tell your loved ones what questions and answers you have chosen. This is probably the simplest way of providing for account succession as it will allow your loved one to reset your account passwords to something they will be more likely to remember. Besides that, the other methods my be a bit too technical for some; good for geeks, but not so good for the gander.
Do give it some thought, will you? The responsible among us urge you to make it easy on your loved ones during what is always a very difficult time.