A cousin passed away few years back with cancer. It wasn't sudden but wasn't expected either. (He was 37 and responding well to treatment). His wife was completely uninterested with regards to finances and bills. He was quite meticulous and wrote down every single account he owned, details like account number, login, password in an excel spreadsheet. It was a lot of help for her. I worry about security of such a syst…
I would encrypt it, store the passphrase somewhere (or tell it to your wife) and put (a link to) the file up on DMS. This way, you have nothing to lose.
Any solution where the sensitive information is physically near me doesn't work well -- what if I die when my house burns down, and my computer and paper documents are destroyed? What if I carefully document everything, store the document encrypted offsite, and make sure my wife knows the password.. and we die together in a car crash?
There needs to be a solution that lives somewhere I don't, and doesn't rely on people I normally accompany on airplanes, in cars, in dark alleyways...
One "what-if" that is super-important to an email-based dead man's switch -- how are your email servers set up for getting email through? I.e, DKIM, RDNS... all of the tricks & protocols that Google uses (and if you don't, you'll end up in the Hotmail junk folder more often than not), processing of auto-replies like Earthlink's whitelist system, etc..