I'm fascinated by some individual people on the internet who have managed to build their own small universes of content: Cosma Shalizi's notebooks, Bill Beaty's science site, Kragen Sitaker's mailing list, John Baez's weekly finds, I could name more but this should already keep you busy for a year or two :-)
Cool list! Some of these are new to me, will have to explore further.
Here's some more:
Wolfram|Alpha - https://www.wolframalpha.com/
Internet Archive - https://archive.org/
WWW Virtual Library - http://vlib.org/
Scholarpedia - http://www.scholarpedia.org/article/Main_Page
Library Genesis - https://libgen.unblocked.ltda/
And some databases...
WordNet (English) - https://wordnet.princeton.edu/
BabelNet (Multilingual) - https://babelnet.org/
Dimensioned drawings/standard measurements - https://www.dimensions.guide/
Aaand some maths stuff...
MathPages - https://www.mathpages.com/
MetaMath (Proofs from scratch) - http://us.metamath.org/index.html
The On-Line Encyclopedia of Integer Sequences - https://oeis.org/
I'm similarly open to criticisms, haven't explored all of these thoroughly but they've all caught my eye over the years for one reason or another.
My list is similar but also includes
This is a great list.
The main criticism I have is that this list overlaps way too much with my own internal list of high-quality sites, making it not very useful.
Below I will present a (small but qualitative ) list of those that I think are some of the best sites/blog that a human being can find on the world wide web.
The main criterion I used to draw up the list was to consider how the websites promote the dissemination of knowledge among people and how, over the course of time, they have helped me both with regards to work and in terms of intellectual self-formation. The order in which they are listed is not to be considered restrictive ( except perhaps for the first two ).
Please feel free to criticize the catalog (as long as the criticisms are rational and constructive) and to expand it in the comments.
1) Stack Exchange Concentrator ( https://stackexchange.com/sites )
2) ArXiv e-Print archive ( https://arxiv.org/ )
3) GitHub ( https://github.com/ )
4) Reddit - the front page of the internet ( https://www.reddit.com/ )
5) LessWrong ( https://www.lesswrong.com/ )
6) Shtetl-Optimized ( https://www.scottaaronson.com/blog/ )
7) Slate Star Codex ( https://slatestarcodex.com/author/admin/ )
8) YouTube ( https://www.youtube.com/?hl=it&gl=IT )
9) TED ( https://www.ted.com/#/ )
10) Standford Encyclopedia of Philosophy ( https://plato.stanford.edu/ )
11) Google Scholar ( https://scholar.google.com/ )
12) SciHub (Banned - no more reacheable on the www from my country)