Phabricator: PHP-based open source platform with code review/hosting, bug tracking, wiki, scrum/kanban board, and more http://phabricator.org/
Pandoc: Command line tool and Haskell library to convert between a number of text file formats http://pandoc.org/
g-wiki: Super simple wiki engine built on Markdown, Go, and Git https://github.com/aspic/g-wiki You had me at Markdown. Demo: http://mehl.no:8081/
