This list will be updated over time with new applications. If you have anything to submit, please comment with your suggestion. This list is dedicated to “mostly” Windows applications although many are open source and/or available on multiple operating systems.
Free Virus, Spy-ware and Mal-ware Removal
Ad-Aware – Find and remove viruses, Trojans, mal-ware and spy-ware.
Spybot-S&D – Checks your system against ad-ware and other system invaders.
AVG – Free anti-virus.
Microsoft Security Essentials – real-time protection for your PC.
Free Alternative Browsers
Firefox – 47% of users use Firefox. The most favored alternative browser today.
Chrome – 16% of users use Chrome. Google’s browser. It’s fast, but lacks features.
Opera – 2.1% of users use Opera. Another alternative browser.
Flock – Centralized photos, videos and updates from your favorite sites such as Facebook or Twitter.
Video: Players, Encoders, Editors
SUPER – Universal player encoder and renderer.
VLAN – The media player that fills all your needs. It can handle DVDs, (S)VCDs, Audio CDs, web streams, TV cards and much more.
GOM Player – plays multiple video formats.
Miro Video Converter – convert almost any video to MP4, WebM (vp8), Ogg Theora, or for Android, iPhone, and more.
KMPlayer – Multi-format media player.
Virtualdub – video capture/processing utility and editor.
Free Video Converter – convert video files between various formats.
Quicktime – Apple Quicktime .MOV movie player.
Audacity – open source software for recording and editing sound.
Music Players and Ripping
iTunes – Audio player with multiple playlist functions, native burn support, visual effects, and file conversion.
WinAmp – free customizable media player that plays mp3 + other audio files, syncs your iPod, subscribes to Podcasts and more.
Antenna – vast list of stations combined with a map interface, you can discover, listen to, and switch between thousands of stations effortlessly.
CDEx – open source digital audio extractor.
Spotify Open – digital music service with access to millions of tracks. Only available in some countries.
Nexus Free Internet Radio – Search and listen to over 15 million songs directly on your PC, or connect to over 11,000+ global radio stations free of charge!
Rainmeter – enhance your Windows computer at home or work with skins: handy, compact applets which float freely on your desktop.
PC: Diagnostic, Repair, Optimization
Soluto – tracks all the applications in your system boot process, and tells you exactly which ones are slowing you down.
GetFolderSize – find out which folders are taking up the most space.
CCleaner – remove unused temporary files, scan and clean the system register, etc.
Auslogics Disk Defrag – free disk defragmentation utility.
Memtest86+ – advanced memory diagnostic utility.
Hijackthis – generates in depth report of registry and file settings. Easily remove unwanted entries.
Ultimate Boot CD (advanced users) – a massive amount of useful utilites on a boot CD.
Defraggler – compact and portable defragmentation.
Messaging, Video, Phone and Conferencing
TweetDeck – a simple and fast way to experience Twitter, Facebook, Buzz, LinkedIn, Foursquare and Myspace.
Skype – free voice, video and text to anyone using Skype.
Trillian – Connect to AIM, Yahoo, MSN, Facebook, Twitter, ICQ, IRC, etc all in one application.
AIM – AOL instant messenger.
Yahoo – Yahoo instant messenger.
MIRC – IRC (Internet Relay Chat) client.
Xchat / Xchat2 – IRC chat client.
Windows Live – Windows live messenger. Previously called MSN Messenger.
Digsby – IM, e-mail and social networks in one application.
Teamspeak – client and server software for voice communication between multiple users.
Ventrilo – client and server software for voice communication between multiple users.
ShareMonitor – monitors access to your network shares.
LogMeIn Hamachi – hosted VPN service that securely connects devices and networks, extending LAN-like network connectivity to mobile users, distributed teams and business applications. You can easily create secure virtual networks on demand, across public and private networks.
Virtualization and Multiple Desktops
Virtualbox – Powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as home use.
VirtuaWin – Virtual desktop manager.
Dexpot – configurable multiple desktops.
Author Recommended Firefox Add-ons
Web of Trust – With WOT the web is a safer experience. Millions of users rate sites by their privacy, trust, child safety, etc and you immediately know how safe a site is. Blocks access to sites the public have decided to be dangerous.
AdBlock Plus – Regain control of the internet and view the web the way you want to (blocks ads).
Downloadthemall – Lets you download all the links or images contained in a web-page and much more: you can refine your downloads by fully customizable criteria to get only what you really want.
IETab – Force specific websites to open in Internet Explorer inside of Firefox (useful for sites that only work in IE).
Utorrent – Fast, efficient and free torrent application.
Notes and Text Editing
Evernote – Save your ideas, things you see and things you like. View them on any device you use.
SublimeText – Text editor for code, html and prose.
Notepad++ – Free source code editor and notepad replacement.
Password Protection and Backup
Keepass – Open source password manager.
7-Zip – Supports 7z, ZIP, RAR, TAR, ARJ, CAB, etc.