18/10/09 GnuPG

GnuPG is the GNU project's complete and free implementation of the OpenPGP standard as defined by RFC4880 . GnuPG allows to encrypt and sign your data and communication, features a versatile key managment system as well as access modules for all ... More info.

  07/07/09 TrueCrypt

Free open-source disk encryption software for Windows Vista/XP, Mac OS X, and Linux. It doesnt get better then this, highly recommended.

More info: http://www.truecrypt.org/
... More info.