Project Gutenberg - Free books
Centsless Books - Free books, newer than Gutenberg's.
OpenLibrary - download out-of-copyright books, borrow in-copyright books, recommended
LibriVox - Free audio books
Podiobooks.com - free audiobooks mostly from self-published authors. recommended
Documentary Heaven - Free documentaries
TopDocumentaryFilms.com and FreeDocumentary.tv - more free documentaries recommended
Last.fm - Keeps track of your listening habits
Songza - Playlists for whatever mood you're in.
Soundozer - it's kind of like Pandora, but you can listen to any song you search for and you can create a station based on that song. You don't have to register either.
Grooveshark - free music, online radio, streaming.
Jango - Free music - internet radio that plays what you want, great for those who can't access
Harvard Open Courseware
MIT Open Courseware
Yale Open Courseware - actual video lectures for the class so you can get the in-class experience. Lots of classes over lots of subjects. recommended by /u/Pantsuit_Ugh
Stanford Open Courseware
EDX - Free courses from the best universities, you can even get a diploma for a few dollars.
Khan Academy - Free maths learning tutorials
Codecademy and LearnStreet - Free interactive coding tutorials
Become a programmer, motherfucker
Duolingo and FSI Language courses- Free language learning
Ted Talks - Free talks and lecture about anything and everything
Wolfram Alpha - Your one stop shop for calculations and questions about anything
Mathway - Awesome math problem solver.
A giant collection of Computer Science books made freely available
FreeRice - Answer vocabulary questions and rice is donated to charity!
7 Cups of Tea - Free online counselling service
Thrive On - Not completely free, but aims to bring affordable online mental health programs to those who would otherwise go without. Starting next month
Blah Therapy - Online listening service. "Experience the rewards of venting to a stranger or lending an ear."
MoodGYM - Learn cognitive behaviour therapy skills for preventing and coping with depression.
Ninite - update/install all your programs at once
SlimDrivers - Cloud based program that detects what drivers need to be updated. Incredible--especially after formatting an operating system. No need for CDs or trying to remember which model card, adapter...etc. you have.
Copy - Online cloud storage. Start with 15gb free. Or 20gb with a referral link (Shameless sharing of my own referral code). Woah, I've got a tonne of storage now.
Mega Desktop Sync(50GB) and Symform (Unlimited, but you must share back!)
Calibre - Free ebook library management
F.lux - Changes the colour of your screen as the day progresses
GIMP - Free photo manipulation software
Paint.NET - Windows application designed to be the much needed upgrade to MS Paint. recommended
Sumo Paint - Powerful graphics editor for your web browser and pc,
Blender - Open source, cross platform suite of tools for 3D creation.
Prey Project - Multi-platform anti-theft software
RES - Reddit enhancement suite - A must have for all you redditing needs
KeePass - free, open source, light-weight and easy-to-use password manager.
LastPass - free (with premium for multiple platforms), easy-to-use password manager.
Dictionary Pop-up extension, double click on a word that you don't know the meaning of and a dictionary definition pops up. Firefox extension powered by dictionary.com. Chrome extension powered by Google
ClipCube - clipboard history. I missed this when using Windows
LeechBlock (Firefox add-on) - simple productivity tool designed to block those time-wasting sites that can suck the life out of your working day.
StayFocused - Chrome alternative to LeechBlock,
Audacity - free, open source, cross-platform software for recording and editing sounds.
MusicScore - Free music composition and notation software.
Notepad++ - Notepad++ is a free source code editor and Notepad replacement that supports several languages.
Sublime Text - a sophisticated text editor for code, markup and prose. r
Rainmeter - Windows desktop customisation.
Handbrake - open source video transcoder
Pocket - a great site for saving articles, recipes or whole pages for later offline viewing, and cloud syncs with all your devices.
OpenOffice - The free and open productivity suite. Free Office
DistroWatch - Put the fun back in computing. Use Linux, BSD. This site gives detailed information on each Linux distribution and provides links to their respective communities.