gutenberg.org - Thousands of free e-books free to read or download in many different formats (e-pub, HTML, pdf, etc.)

neilarey.com - A fitness and overall healthiness website that is completely ad and product-placement free. It provides you with visuals of workouts, free meal guides, and it even with easy recipes.

tabletopaudio.com - While this site was originally intended as a resource for players and GMs of tabletop role-playing games, Tabletop Audio is for: Role-players, boardgamers, writers, coders, artists, graphic designers, teachers, house-cleaners, lucid dreamers, gym-rats, distance runners, commuters and ANYONE who wants to immerse themselves in the audio-space of one environment, while physically inhabiting another. On the main page, you will find dozens of 10-minute, situational audio files called ambiences. Press play. Listen.

alternativeto.net - Lets you find alternative software to any program. Just type in the name and find alternatives.

flixfindr.com - Enables you to browse through a never ending scroll of movies from all of your subscription services (Amazon, Netflix, Hulu, Xfinity, HBO GO) simultaneously. Sadly this only shows movies and not TV series.

ibrivox.org - Lets you stream or download thousands of free public domain audio books, read by a community of volunteers. Since they are read by volunteers some aren't the best but there are tons of excellent readers.

duolingo.com - An excellent website for learning new languages. It is very intuitive and easy. You can make a profile to save your progress for free.

openstaxcollege.org/students - An awesome website that lets you view or download college text books. It is completely free and legal, and is actually partially funded by the Bill & Melinda Gates Foundation.

archive.org - For everything public domain; books, movies; TV shows, music, games. If it's public domain, it's here.

asoftmurmur.com - Lets you adjust the levels of different sounds (rain, thunder, fire, etc.) to make the perfect ambiance.

citethisforme.com - Probably the easiest way to cite books, websites, newspapers, etc. Just type in the name of the work and it does the rest. There is a premium version but I have only used the free version. I only wish I had this when I was in high school.