Shardul Chiplunkar

MathILy (and MathILy-Er), an enriching and very fun math camp; the same people run an REU-style program called MathILy-EST
SPARC, the Summer Program on Applied Rationality and Cognition
Panini Linguistics Olympiad, linguistics contest for Indian high schoolers, feeding into the International Linguistics Olympiad (IOL)
Monsoon Math Camp, an Indian math camp for high schoolers
Euler Circle, math circle in the SF Bay Area
Bhaskaracharya Pratishthana, math circle and other math activities in Pune, India
The Recurse Center, “a self-directed, community-driven educational retreat for programmers”
MIT Educational Studies Program, educational programs for Boston-area middle- and high-schoolers

Language Log, linguistics blog
IPA keyboard
IPA chart with sounds
Khandbahale, online Indian multilingual dictionary
Webster’s 1913, digitized and fully searchable version of Webster’s Revised Unabridged Dictionary, ed. Noah Porter, pub. C. & G. Merriam Co., Springfield, MA, 1913; “[c]onnoisseur’s reference to American English — a dictionary for writers and wordsmiths”
Pink Trombone, interactive sound-producing model of the vocal cavity
Digital Dictionaries of South Asia, fully searchable; Marathi ones are quite good (I haven’t used any others)
learnsanskrit.cc, online Sanskrit dictionary
Panini Linguistics Olympiad, linguistics contest for Indian high schoolers
Different possibilities to write words with voice by Tran Quang Hai

Questionable Content (no, it’s not NSFW) sitcom-style but with sentient robots
Wondermark, absurd humor with Victorian visuals
Strong Female Protagonist, superheroes and supervillains and moral dilemmas (the protagonist is a female who is strong)
Subnormality, extremely detailed artwork with often deep social commentary, not your typical comic
The Perry Bible Fellowship, charming art and offbeat punchlines
xkcd, very nerdy
Saturday Morning Breakfast Cereal, also nerdy and often dark

Harry Potter and the Methods of Rationality (HPMOR) by Eliezer Yudkowsky. The only fanfic of any kind that I’ve ever liked. ‘What if Harry Potter was a rationalist?’
Worm and Pact, two webserials by wildly successful debutant Internet author ‘wildbow’. The premise of Worm is superpowers in a very imperfect, human world, from city blocks to planetary politics; the premise of Pact is dealings with the supernatural, who have a polity of their own.
UNSONG: ‘What if Kabbalistic Judaism were true, in a power-hungry capitalist world?’ By Scott Alexander, roughly in the genre of rational fiction, very engaging.
What football will look like in the future – 17776, football but also science fiction.
SCP Foundation, a sprawling, wiki-style collection of stories set in a universe with mysterious supernatural artifacts ‘secured, contained, and protected’ by the Foundation.

Rajan Parrikar’s Music Archive is both a curated archive of thousands of rare, old, Hindustani classical music recordings, and a large collection of artful blog posts about Hindustani classical music from a seasoned connoiseur.
SwarGanga has handy tools to search for raags or bandishes by their notes.
Aathavanitli Gani has a huge collection of lyrics and metadata about Marathi songs.
The Darbar Festival YouTube channel has high-quality recordings of modern classical artists.
Rahul Deshpande has an audioblog about Hindustani classical music: facts, opinions, and stories interspersed with short vocal demonstrations. (This used to be on his now-defunct website.)
Renditions of The Star-Spangled Banner
- Ah, yes, jazz
- Credit card machines
- Ah, yes, rock (listen until at least 1:18 for the full experience)
Renditions of Pachelbel’s Canon in D

Far from a complete list…