The HoTT Book: Homotopy Type Theory: Univalent Foundations of Mathematics has been released under CC-BY-SA! More about it at the official announcement, the n-Category Café, Robert Harper, and Andrej Bauer.
Some Domain Theory and Denotational Semantics in Coq, by Nick Benton, Andrew Kennedy, and Carsten Varming.
Quasicrystals and the Riemann Hypothesis, John Baez: “If some random dude said the Riemann Hypothesis was connected to quasicrystals, I’d probably dismiss him as a crank.”
Build System Rules and Algorithms (PDF), by Mike Shal (2009). Makes an important distinction in how the order of dependencies should be tracked in build systems.
Buck is a build system for Android (and Java in general) that encourages the creation of small, reusable modules consisting of code and resources. Uses a bottom-up dependency model, by Facebook.
Pants is a build tool using a bottom-up dependency model, by Twitter.
Building Scala Hygienically with Pants, talk by Mark Chu-Carroll. (Also rants on too smart build systems.)
Build in the Cloud: How the Build System works at Google (2011), describes Blaze, the build system that strongly influenced Buck and Pants. (Also, see Coding and Testing at Google, 2006 vs. 2011.)
Siren is a text-based audio player for UNIX-like operating systems. Various aspects of Siren have been inspired by cmus. Siren is distributed under the ISC licence.
Quipper is an embedded, scalable functional programming language for quantum computing.
arm-js is an ARM emulator written in Javascript. It can boot Linux 3.6.1 and run busybox processes, and uses virtio-9p to communicate with the HTML5 file system API.
hlld is a high-performance C server which is used to expose HyperLogLog sets and operations over them to networked clients.
sshbox is a utility to encrypt and decrypt files using OpenSSH keys.
Love is all, by Alejandro Gómez-Arias (NSFW): “Every love is an exercise of depersonalization on a body without organs yet to be formed.” (Deleuze & Guattari).
Monday, June 17, 1963: ASCII, the original diagram.