Thanks! I celebrate weird hobby web sites. Here are some of my favorites:

* 59828 different definitions of "triangle center" https://faculty.evansville.edu/ck6/encyclopedia/ETC.html

* Amazing reference on bezier curves https://pomax.github.io/bezierinfo/

* Sunbeam radiant toaster http://automaticbeyondbelief.org/

* How to pack geometric shapes inside other shapes https://erich-friedman.github.io/packing/

* Pictures of library cards https://librarycards.tripod.com/id1.html

* All about pc fans https://nick-black.com/dankwiki/index.php?title=PC_Fans

* Cross sections of candy bars https://scandybars.tumblr.com/

* All kinds of info about bicycles https://www.sheldonbrown.com/

* Every type of plastic used by lego https://bricknerd.com/home/every-type-of-plastic-used-by-leg...

* Ian's Shoelace Site https://www.fieggen.com/shoelace/

> How to pack geometric shapes inside other shapes https://erich-friedman.github.io/packing/

Packing / bin-packing is very serious stuff: savings made there directly translate to less waste / reduced costs (for example when cutting shapes into sheets of metal in big factories).

> * Amazing reference on bezier curves https://pomax.github.io/bezierinfo/

And some beautiful graphs in there, notably those under section 26 "Curvature of a curve". Screenshot'ed for my own collection of good looking stuff!

Another one of my favorites has disappeared recently :-(

"the sierpinski triangle page to end most sierpinski triangle pages ™" — but it's still on wayback machine https://web.archive.org/web/20190322201106/https://www.often...