[hhm]

Steganography is always interesting for data storage. It is pretty easy to hide data into pretty much any medium.

See http://jthuraisamy.github.io/markovTextStego.js/ and https://github.com/hmoraldo/markovTextStego

[chrissnell]

Combining steganography with Reddit could be interesting. Random (mildly interesting) photos pushed to imgur and posted to /r/pics by the same user every time.