Use of digest and or checksums
I also shutdown after each use, and everytime I bootup I need to enter 4 different passwords to get a working environment. First is HDD BIOS password, then BIOS System password, then GRUB menu password (SHA512), then Windows logon password, then some private archives were also encrypted. This is just a personal laptop with nothing to protect except my daughters photos and some banking PDF files which are also password-protected by the bank itself.
On the othe rhand, I think any type of encryption used by the owner on his/her documents and private stuff would make this types of cold b oot attack useless. Even zip encryption or .7z compression with strong crypto would defend against this cold boot attack, as long as the password is not stored in any plaintext documents sitting on the filesystem.