Ask HN: Share your fav quirky, weird, interesting websites (like postcrossing)?

One of my favorites is postcrossing.com - a huge community of people interested in postcards. some 65 million postcards sent, tons of friendships formed, thousands of meetups etc. I'd have never guessed that so many people can be so passionate about postcards - I doubt most young people today have sent/received even a single postcard.

What are some of your favorite corners of the web? There was one site where someone was digitizing tens of thousands of newspapers all by himself, one where a couple (I think) wrote passionately about various plants... I forgot to bookmark them, my bad.

Anyway, please share your favorites and why. Not just websites, apps are good too. I am tired of going to the same websites everyday (reddit, some youtube channels...) - would be nice to discover projects that are primarily born out of passion, unlike the 99.99% of the web whose primary goal is money.