Graphics
Blender - 3D content creation suite
Gimp -  Image Manipulation Program

Chat
Pidgin - IM Chat Client Program for MSN/ICQ/AIM/Yahoo etc...
aMsn -  MSN Chat Client

Video/Media
DVDVideoSoftware - Video ripping/editing/conversion software's
FlvPlayer4Free - Very Handy FLV Player for your desktop
Miro - OpenSource Free Video Player
VLC Media Player - OpenSource Multimedia Player
Mplayer - Video Player
HandBrake - Video Converter
Performersoft - Video Converter

Apps
OpenOffice - OpenSource Alternative for Miscrosoft Office Package
LibreOffice - OpenSource Alternative for Miscrosoft Office Package
Calligra-Suite - OpenSource Alternative for Miscrosoft Office Package
AbiWord - free word processing program similar to Microsoft® Word
AllwaysSync - Allway Sync is free file and folder synchronization software for Windows.
FileZilla - OpenSource FTP Client / Server
WinSCP - OpenSource FTP / SFTP / SCP Client
TurboCash - Accounting Program
TightVNC - Free, Lightweight, Fast and Reliable Remote Control Software
RealVNC - provides remote control software which lets you see and interact with desktop applications across any network.
Putty - Telnet / SSH client
WinSSHD - Not OpenSource but free. SSH Client
Poderosa - SSH Client

Security
TrueCrypt - Best Encryption Software
Eraser - Secure Erase Files
BleachBit - Clean junk to free disk space and to maintain privacy
Gpg4Win - ... for file and email encryption.
Nixory - free and open source antispyware tool written in Python/PyGTK aimed at removing malicious tracking cookies from your browser.
Asrar - Mujahideen Encryption Software

Trojan Scanner / Remover
A Squared Free - Scan and remove especially trojans and other malware such as worms, viruses, spyware, trackers, dialers, etc.
PC Tools ThreatFire - Proactive defense against both known and unknown threats by trojans as well as viruses, worms, spyware, rootkits and other malware.

Anti-Virus
Avira AntiVir Personal Edition - Top pick for best free antivirus program, outstanding detection of malware, light on resources
Avast! Free Antivirus - Full real-time capabilities, low rate of false positives, fairly light on resources, boot-time scanning
A-Squared Free - Outstanding detection, context-menu scanning

Firewall
Comodo Internet Security - Its Defense+ HIPS performance exceeds commercial products and leads the class.
Online Armor Free - Excellent proactive security performance.

Education
Celestia - The free space simulation that lets you explore our universe in three dimensions.
Stellarium -  It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope.
Free OpenSource Education - Links to free Education Software's

Programming
DragonFireSDK - Windows Iphone Programming
AppMaker - IPhone Application Maker

CD/DVD Burners
InfraRecorder
ImgBurn
CDBurnerXP
BurningMill
CDRTFE
TotallyFreeBurner
Inscriptio
BurnOnDVD
FinalBurner (free version available)
DeepBurner (free version available)
StarBurn (free version available)

OS (Operating Systems)
BackTrack Linux (very secure)
DistroWatch (lists of linux distros)
Linux Mint (out of the box, Ubuntu compatible)
Ubuntu (wide support, popular)
CentOS (good for servers)
Fedora
Debian
FreeBSD (operating system for the i386, IA-64, PC-98, Alpha/AXP, and UltraSPARC platforms)
PCLinuxOS (out-of-the-box support for many popular graphics and sound cards)
PuppyLinux (extreme small and fast)
Linux Mint (based on Ubuntu, out of the box, inlude codes, plugins and other components)

Other
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