[noir_lord]

Two keys, you put one on memory sticks which you give to friends/family you trust.

In the event anything happens to you the other key is sent to those people allowing them to decrypt it.

Service can't access your data as it only has one and same for trusted person.

I'm sure something like this already exists (and tbh the level of effort required to set it up pretty much makes it unlikely to catch on) but it is theoretically workable.

[bentcorner]

You don't need any keys. Just say "I wrote how to log into my email on a piece of paper in the safe deposit box. You may have found it already."

[mitochondrion]

But that doesn't have enough points of failure!

[jlgaddis]

For those of us who run FreeBSD, there's gshsec(8):

http://www.freebsd.org/cgi/man.cgi?gshsec

Want to set up a "2 of 3" (or similar) scheme? You could use, for example, a three-disk RAID5 using USB flash drives.