Tim Caswell has several projects that interact directly with git. He has a few websites served directly from a bare git repo powered by https://github.com/creationix/wheaty. Another project that uses git as a storage medium is a package server for the node.js API implemented in Lua: https://github.com/luvit/lit.

Both serve files from a git repository, and lit will actually write to the repository. There are several others that Tim has built over the years, but those are the two that I am familiar with.