mini-git-server - a pure-Java WAR capable of hosting git repos and exposing them with git+ssh. Basically a copy of Gerrit (http://code.google.com/p/gerrit/) - with all the review-related functionality stripped away and the dependency on a database removed (making it entirely filesystem based). I use it for integration-testing my git client.
Homepage POM file JAR file Javadoc'com.madgag:mini-git-server-parent:0.2'