Julia Evans' blog, mostly coding and whatnot https://jvns.ca/

Distill Pub which has interactive machine learning papers, here is a good one https://distill.pub/2020/grand-tour/

this tumblr that posts old videogame ads https://retrocgads.tumblr.com/

http://crouton.net

https://www.jstpst.net/

https://realkanji.com/ for studying jlpt n5 - n1 kanji

http://bilinguis.com/ a few public domain books with multiple translations for comparing side-by-side

https://ciudadseva.com/biblioteca/indice-autor-poemas/ huge collection of poems in spanish

I like pz meyer's blog. he talks about social justice and spiders, so it's a good fit for me!

neat collection of serial experiments lain fan-made "web art" (i do not know how else to describe it). seizure warning applies. https://fauux.neocities.org/

algorithmically generated scatter plot of musical genres/subgenres. http://everynoise.com/engenremap.html

a repository of fan translations of classic chinese wuxia novels. https://wuxiasociety.com/

https://www.copypastecharacter.com/ is a useful character map (I know there's one built into windows but I find this more convenient due to the way it sorts stuff)

https://thealexandrian.net/ is a blog by a guy who's been GMing tabletop RPGs for yonks, and wrote the Infinity RPG among other things. Lots of good resources on GMing there, and it always gets me in the mood to run a game when I read it.

http://radio.garden/ let's you listen to live radio broadcasts from all over the world with a neat user interface

http://pica-pic.com/ has a bunch of accurate flash recreations of old handheld games from the 80s playable in-browser

https://belowthesurface.amsterdam/en/vondsten is an archive of items found in a drained canal in Amsterdam, ranging from modern electronics to ancient tools and pottery. Many of the items are hundreds of years old, with the oldest ones dating back thousands of years, and each one has photos and detailed information about the objects.

https://mynoise.net/noiseMachines.php has a wide selection of different ambient noises that are great for background noise or as white noise for sleeping. A lot of them require a one-time donation to access, but there's tons of free ones to choose from as well.

Doesn't exactly fit with the "not big" rule, but Wikipedia's List of Unusual Articles can be a great time waster.

http://arena-7.appspot.com/

Loved the Arena games as a kid! Arena 5 (I think) was a Visual Basic masterpiece imho.