This guide offers the least time-consuming way of setting up Nginx for serving Git repositories over HTTP using Gitweb. The stuff here has been tested with Git 1.9.1 and Nginx 1.6.0 on Debian Wheezy. Probably also works for Ubuntu, etc.
Total time ~ 10 minutes.
wheezy-backports by adding this line to
deb http://http.debian.net/debian wheezy-backports main