Vdirsyncer is a command-line tool for synchronizing calendars and addressbooks between a variety of servers and the local filesystem. The most popular usecase is to synchronize a server with a local folder and use a set of other programs to change the local events and contacts. Vdirsyncer can then synchronize those changes back to the server.
MkDocs is a fast, simple and downright gorgeous static site generator that's geared towards building project documentation. Documentation source files are written in Markdown, and configured with a single YAML configuration file.