A free tech magazine. I don't know how practical the one page per article constraint is, but it is fun and I'm enjoying Issue 8 so far.

ants as enemies in science fiction

A good series on how sensitive accuracy is to various factors of marksmanship (group tightness, consistency of ammo velocity, cartridge selection, wind calls...)

tom7's videos and SIGBOVIK papers are treasures

http://tom7.org/

Tic-Tac-Toe in static HTML

As seen by Bob Hearn (in 2003)

I bought John Langdon's book Wordplay years ago, but a recent discussion on hacker news reminded me of ambigrams

https://news.ycombinator.com/item?id=38477259

Graphing calculator emulators on the Internet Archive.

Very nice online gif editor/convertor