Enigmail is an extension to the mail client of Mozilla / Netscape and Mozilla Thunderbird which allows users to access the authentication and encryption features provided by GnuPG
OTR allows you to have private (not just encrypted) conversations over instant messaging by providing: Encryption, Authentication, Deniability, and Perfect forward secrecy.
The Gpg4win project aims at updating the Gpg4win Windows installation package with GnuPG encryption tool, associated applications and documentation on a regular basis.
The GNU Privacy Guard (GnuPG) enables people to securely exchange messages and to secure files with both privacy and strong authentication. GnuPG is a free software replacement for the PGP suite of cryptographic software.
Portable Gaim is the versatile Gaim instant messaging client packaged as a portable app, so you can take your IM settings and buddy lists with you. The Off-the-record plugin is also included for secure, encrypted messaging
Portable Thunderbird is the popular Mozilla Thunderbird email client packaged as a portable app, so you can take your email, address book and account settings with you.
TrueCrypt is a free open source on-the-fly encryption (OTFE) program for Microsoft Windows XP/2000/2003 and Linux. It allows one to create a virtual encrypted disk within a file and then mount it as a real disk
VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols.
CCleaner (Crap Cleaner) is a freeware system optimization and privacy tool. It removes unused and temporary files from your system - allowing Windows to run faster, more efficiently and giving you more hard disk space.