Personally I had the idea a while back for a sort of time-release dead drop. Stuff a Raspberry Pi into a fake power strip, put your seekrit information onto the SD card, and go plug it in somewhere in a city you 'happen' to be passing through, near to a public wifi spot.

Then a year later it wakes up and uploads the data publicly via Tor and self-wipes. Even if it's traced back to the Pi, they'll have to trace the Pi back to you (you bought it untraceably, right?).