A good Live CD. It has everything you need from the command line to mount/unmount and encrypt/decrypt hard disk and USB partitions. Even has gparted for changing disk partitions and formating. I even was able to mount by bluray USB optical drive and make a backup image of my harddisk partition. Granted the command line for doing that is cryptic, but nonetheless, This cd had everything i needed out of the box for doing that and it fits entirely on a CD-ROM making for a fast download.
I even use it as crude word processor by opening files in a text editor when i fear that my computer has been compromised with viruses, then save them on luks encrypted partition that is easily mounted and unmounted from the command line.