I like the idea of having a separate decryption device. OS reads encrypted data from hard disk, sends it over an encrypted link to your cell phone, which partially decrypts the data block (using one pass phrase), and sends it back over the encrypted link to the laptop. OS driver then finishes decrypting that block using a second key before passing it to your program. Writing back data just requires a public key, so write operations don't have to go to your cell phone. The idea is that your drive would never be fully unlocked, and the computer wouldn't ever have the full decryption key on it (neither would your phone).
Add in the always-on voice recognition that some Android phones have, and have the key wipe itself as soon as it hears "Freeze... FBI".
Add in the always-on voice recognition that some Android phones have, and have the key wipe itself as soon as it hears "Freeze... FBI".