skalibs is a set of general-purpose, low-level C libraries, all in the public domain. It can replace or hide the standard C library to some extent. It is designed to allow building of small static binaries. It is used in building all skarnet.org software, including execline and s6.
Simulated annealing is a computational algorithm for optimization. It mimics the physical process of thermal annealing in which a metal is heated and then slowly cooled to settle into a highly ordered crystal structure. For common metals, the lowest energy state is already known. But the method is useful for other problems where the best state is not known and exhaustively searching all possible states is impractical. The method is applied by modeling the problem as a physical system with structure, energy, and temperature. This Python module implements simulated annealing so that it can be easily applied to a variety of problems. An example program is include to perform simulated annealing of the traveling salesman problem.
spectrwm is a minimalistic tiling window manager that tries to stay out of the way so that valuable screen real estate can be used for much more important stuff. It has sane defaults and does not require one to learn a language to do any configuration. It was written by hackers for hackers and it strives to be small, compact, and fast.
s6-portable-utils is a set of tiny general Unix utilities, often performing well-known tasks such as cut and grep, but optimized for simplicity and small size. They were designed for embedded systems and other constrained environments, but work everywhere. Other sets of small utilities are usually system-specific; for instance, the (otherwise excellent) BusyBox project only works on Linux.
oed2dict is a set of scripts that convert the full Oxford English Dictionary v2 (CD-ROM version 3.0) into the jargon and DICT file formats. These can then be consulted with any DICT compatible dictionary lookup program. The resulting DICT files are much faster to use when compared with the proprietary program from the original distribution, and are significantly smaller, with the whole database only weighing around 190MiB.