Gitdocs
Open-source Dropbox using Ruby and Git
...The service watches selected local directories and automatically commits and pushes changes to configured remote repositories. Existing repositories can be monitored, or Gitdocs can clone a remote repository and create a new synchronized share. A browser interface lets users explore files, view revision histories, revert changes, edit text, upload content, and preview supported formats. Git provides merging and historical tracking, while conflicting document versions are preserved for manual resolution when automatic merging fails. The project is particularly suited to notes, wikis, plans, code snippets, and other text-oriented collaborative material.