Security:

• Ad-aware - Spyware remover
• AVG - Virus scanner
• PGPdisk - Disk encryption utility
• SpamBayes - Spam filter
• SpamPal - Spam filter
• SpyBotSD - Spyware remover / realtime monitor
• Windows Privacy Tools / GnuPG - Encryption utility
• ZoneAlarm - Firewall

• Mozilla Firefox - Internet browser
• Mozilla Thunderbird - Mail client

• Audacity - Sound editor
• GIMP - Image editor
• Video Lan Client player - Video viewer
• XnView - Image viewer

• CutePDF - PDF printer
• OpenOffice - Office applications
• FreePDF - PDF printer

• Ethereal - Network sniffing
• IzArc - ZIP/RAR/ARJ/etc program
• PuTTY - SSH client
• TightVNC - Remote access (VNC)
• WinSCP - File transfer using SSH
• Xvi32 - Hex editor

• Cygwin - *nix-style commands on Windows
• DAEMON tools - use disk images as just another drive

• vim - My editor of choice

• Azureus - BitTorrent client
• Trillian - Instant messaging: ICQ, MSN, Yahoo, AIM, IRC