A friend of mine looked into this a couple of weeks ago, and his solution is rather creative and in a similar vane to Hayduke's (comment #17). His laptop runs linux, so he created another partition that is only mounted when a specific USB flash drive is attached to his machine. Since, it is not listed in fstab, the only way to find it without the usb key is to look at the partition table. Also, he has it mount on his home directory, so anyone looking at his home directory without the hidden partition mounted just sees some rather inoccuous documents.