Pick a nice, long, secure passphrase. Use it to secure a GPG keypair. Back up this keypair in multiple locations, and with multiple people who know "This is the key that encrypts all of my digital stuff. My family will need it when I die.".
Use that keypair to encrypt all of your important passwords and data. Back up the encrypted files in multiple locations. Make sure your family knows where these locations are, and why thy and the files they contain are important.
Download a copy of http://passguardian.com/ . Load the saved copy (preferably in an offline PC) in a browser, and use it to convert your passphrase into several N of M parts. ie: Create 10 parts, and require at least 6 to reconstruct the passphrase.
Use something like http://goqr.me/ (or any other generator) to create QR codes for the 10 secret shares. Laser print the text share, QR code and some instructions onto a business card sized piece of paper, and have them laminated.
You now have 10 waterproof, hard to damage cards, any 6 of which will unlock your digital data. Distribute them to trusted parties and locations with instructions to use the shares once they hear and confirm your death. These parties don't have to be literate enough to merge and decrypt the data themselves, they just need to know that it is possible with their share. On your death, they will arrange to bring the shares and data together, and even if they have to hire a nerd to help them, they will unlock what they need.