VLC - Open source video player.
Media Player Classic - Home Cinema - Light-weight media player for Windows. I personally like MPC-HC much better than VLC. Supports more codecs/formats and video looks better.
Combined Community Codec Pack - A simple playback pack for Windows with the goal of supporting the majority of video formats in use today. Must have if you watch certain tv-shows or anime.
Foobar 2000 - Extremely lightweight and customizable free audio player for Windows. Supports a wide array of different audio formats.
Audacity - Free, open source, cross-platform software for recording and editing sounds.
Spotify - Listen to music for free.
Reddit Enhancement Suite - Make surfing Reddit so much more enjoyable. Highly customizable and easy to set up.
Adblock Plus - Blocks annoying ads on webpages and in videos. Surf faster and safer.
Ghostery - Anti ad/tracking extension.
ProxTube - Circumvent blocked Youtube videos.
Speed Dial - Allows fast access to your most visited websites. Extremely useful if you visit or want to keep track off a lot of different websites.
NoScript - Open source add-on (for Firefox) which allows JavaScript, Java, Flash and other plugins to be executed only by trusted web sites of your choice.
ScriptSafe - Similar to NoScript only for Chrome instead.
Search by Image for Google (Firefox) - Fast way to reverse search an image. Very handy if you're looking for a source, more information or if anyone posts "original content".
Search by Image for Google (Chrome)
Microsoft Security Essentials - Lightweight antivirus software.
Avast! Free Antivirus - Antivirus software.
Malwarebytes - Anti-malware software.
TrueCrypt - Free open-source disk encryption software for Windows 7/Vista/XP, Mac OS X, and Linux.
Keepass - Free, open source, light-weight and easy-to-use password manager.
LastPass - Another password manager that makes web browsing easier and more secure.
CCleaner - A freeware system optimization, privacy and cleaning tool. For Windows and Mac.
Defraggler - Defragmentation software for Windows.
Recuva - File recovery software for Windows.
Speccy - Give you detailed statistics on every piece of hardware in your computer. For Windows.
Skype - Call friends/family on their computers or phones. For Windows and Mac.
Pidgin - Open source chat client which is compatible with several different chat networks.
Trillian - A fully featured, stand-alone chat client that supports several different chat networks.
HexChat - IRC chat client for both Linux and Windows.
Foxit Reader - Free PDF reader for Windows, Linux and smartphones.
Sumatra PDF - Free PDF reader for Windows.
Open Office - Open source personal productivity suite.
Libre Office - Open source personal productivity suite for Windows, Mac and Linux.
GIMP - Free image manipulation software.
Paint.net - A free image and photo editing software. For Windows.
IrfanView - The best freeware image/graphic viewer for Windows. Extremely lightweight and supports a wide arrange of different formats.
