[2to15characters]

Any of the Explorable Explanations that Bret Victor creates. Later followed up by more from Nicky Case, and more

[msaharia]

All the links I clicked led to other websites. Is it an aggregator?

[trendoid]

What you saw probably was the collection created by Nicky Case. Check his own explanations though https://ncase.me/ and then also check http://worrydream.com/#!/ExplorableExplanations (and other explanations by Bret Victor)