The protobuf wallets now used in bitcoinj/multibit are quite small. A one key wallet with 30 transactions is only 25KB.
This makes it possible to
steganographically hide a wallet in an image, audio file or video.
You could create a
steg wallet by embedding a wallet into one of your holiday photos.
With a password to AES encrypt the data before you hide it, the data would just be visually imperceptible noise in the image.
A hackbot would then have to look through all your images/ audio/ video and look for the particular noise signature before extracting what it thinks is a wallet and then bruteforcing it. To make life more difficult for the attacker you can add random noise to all the rest of your images/ audio/ video with the same structure as the steganography encoding. Every media file you owned would then be potential wallet holder and the attacker would have no idea which was the real one.