Slate is a open source project that converts markdown into two-column API docs. Used by NASA, IBM, Sony, Mozilla, and others. I created it during an internship at TripIt in 2013.
Flexblocks is a minimal CSS layout library that tries to simplify and solve common bugs with spacing and aligning elements. You can read the explanation blog post on this site.
middleman-php allows the use of PHP as a templating language in the static site generator Middleman.
learnllvm is a in-progress toy compiler written in Rust with LLVM.
Mortalical and Mortalitab are two little mementos mori in the form of a wall calendar and Chrome extension.