musl is lightweight, fast, simple, free libc implementation. It strives to be correct in the sense of standards-conformance and safety and is available under an MIT license.

Collection of software to make NSA's spying more difficult.

PyEphem provides scientific-grade astronomical computations for the Python programming language. Given a date and location on the Earth’s surface, it can compute the positions of the Sun and Moon, of the planets and their moons, and of any asteroids, comets, or earth satellites whose orbital elements the user can provide. Additional functions are provided to compute the angular separation between two objects in the sky, to determine the constellation in which an object lies, and to find the times at which an object rises, transits, and sets on a particular day.

The numerical routines that lie behind PyEphem are those from the wonderful XEphem astronomy application, whose author, Elwood Downey, generously gave permission for us to use them as the basis for PyEphem.

SPD is a CLI-based password manager, written in Perl and using GnuPG to encrypt its data.

Simple, high-reliability, distributed software configuration management. An interesting DSCM system which is bases on a single executable (written in C), uses SQLite as repository and includes both a wiki and a ticket system. Not related to the Plan 9 file system of the same name.
https://fossil-scm.org/home/doc/trunk/www/containers.md#security describes some ways to run fossil in a container for improved security. This link was found on the PiDP-11 mailing list https://groups.google.com/g/pidp-11/c/OQADvv-sCzU/m/J7zbwITWAgAJ

Hassle-free delivery of a multi-file Lisp program. A simple alternative to ASDF. From Dorai Sitaram, author of "Teach yourself Scheme in fixnum days", scm2cl, TeX2page and other interesting things.

The Giant ANTS for Plan 9 are a collection of software for making Plan 9 systems more reliable and flexible by leveraging the power of namespaces. Includes a demonstration which runs under the Qemu virtual machine.

surf is a simple web browser based on WebKit/GTK+. It is able to display websites and follow links. It supports the XEmbed protocol which makes it possible to embed it in another application. Some of the other programs on the site are interesting too.

Interesting discussion about venti, the Plan 9 block store, including three implementations.

Home page of Kazu Yamamoto, author of some interesting programs such as Firemacs (Emacs key bindings for Firefox), Goby (presentations with Emacs), pgpdump and others.