All external drives, striped across several ...
I have my collection on all external drives, so I can move them across systems. This includes the home directory of my "porn account," which is self contained in the stripe (other than the /etc/passwd entry for the account). They are software striped RAID-0 under Linux, requiring a user to connect them all and then scan for the array and mount it to see the volume. Otherwise, it looks like a junk partition, totally unreadable. Not exactly what the common person would do, especially since I put a smaller, "distracting" FAT32 partition on them. So if someone plugs them in, that FAT32 volume comes up in their desktop (Linux, MacOS X or Windows).
Total size? 600GB currently. Every few months I back up one array to another set. So if I lost a set I'd only be set back a few months.
I used to encrypt the entire array, but that gets quite slow and a single byte error can destroy it. This is much, much faster, and effective enough so the lay person doesn't see the volume.