Re: Just write it down
My dad did this for my mom, with passwords for banks, credit cards and retirement accounts, and provided copies to my brother and I in case they were both in a car crash or something.
Not that any of us can read his handwriting... I was going to suggest typing it, and then updating the copy as needed, until I realized that would provide quite a juicy target for malware that made its way onto his PC. The proper way to handle that is to keep it on a USB stick (and hope that LibreOffice doesn't keep temporary files laying around on the PC after editing such files) but that's getting pretty complicated for him.
He uses his PC for email, bridge and paying bills...I'm already worried he'll get malware that will steal his passwords when he logs in to his credit card or retirement account, but the idea of having him login to those from a VM is a complete non-starter - he'd never understand that. If only Bridge Baron ran on Linux, I'd update his PC while he was away on vacation and tell him it was a new version of Windows - he'd never know the difference :) Maybe I should see how it runs under VMware Unity mode.
As with every good idea, there may be unintended side effects...