On-line calculator for the position of the sun. Appears to be written in Frink https://futureboy.us/frinkdocs/, a language which can evaluate expressions with units.

Found on Tony Finch's link log https://dotat.at/:/
There is also a nice introduction to TCP sockets at https://woozle.org/papers/sockets.html

The purpose of this lattice LOLSMacs tries to configure Emacs never to break the  Law Of Least Surprise (LOLS).

Boot an UEFI machine over the network using the Plan 9 protocol.

envs.net is a minimalist, non-commercial
shared linux system and will always be free to use.

we are linux lovers, sysadmins, programmer and users who like build
webpages, write blogs, chat online, play cool console games and so much
more. you wish to join with an small user space? send a email
to hostmaster@envs.net or use the signup form.

Found via tildeverse.org

Gemini is a new, collaboratively designed internet protocol, which explores the space inbetween gopher and the web, striving to address (perceived) limitations of one while avoiding the (undeniable) pitfalls of the other.

Found via Alex Schroeder's page https://alexschroeder.ch/wiki/Gemini

NomadBSD is a persistent live system for USB flash drives, based on FreeBSD®. Together with automatic hardware detection and setup, it is configured to be used as a desktop system that works out of the box, but can also be used for data recovery, for educational purposes, or to test FreeBSD®'s hardware compatibility.

Blog article about configuring and using the GNU privacy guard gpg, the password manager pass and Emacs, found via Sacha Chua's blog.

Interesting blog written in org-mode, using https://github.com/bastibe/org-static-blog, written by Bastian Bechtold https://bastibe.de/
Some highlights:
https://jao.io/blog/eww-to-org.html convert HTML to orgdown
the links below probably need to be edited, removing the date
https://jao.io/blog/literate-programming.html literate programming
https://jao.io/blog/signel.html, a barebones signal chat on top of signal-cli, written in literate style
https://jao.io/blog/programmers-go-bananas.html category theory
https://jao.io/blog/dancers-at-the-end-of-time.html sounds like an interesting book.
https://jao.io/blog/geometrically-speaking.html geometric proofs, Kindergarten Quantum Mechanics
https://jao.io/blog/observatory.html Mozilla Observatory to check a website's security
https://jao.io/blog/simple-note-taking.html simple note taking

Just what it says. A 4 GB Rπ costs £8.63/month ≈ €9.57/month.