What resources have you used to prepare a "what my family should know" file?

Our lives can change in a second. Even if we feel fine right now, anything can happen tomorrow or even later today. At some point it makes sense to be sure that someone knows how to find our important information and property in case we become seriously ill or die.

My husband and I have made our wills, but there is a lot of stuff we’ve never spelled out or organized before: for instance, where’s the title to my car, how do you close my online accounts, whom do you notify, what do I want done with my (—) collection? It’s time to do that.

If you’ve been through this uncomfortable process yourself, are there any particular tools or checklists or resources that you’ve found especially helpful?

Tags as I wrote them: wills, illness, death, getting affairs in order, final wishes.