Configuring Gitweb for Apache on Debian

git.ithinksw.org is a pretty nifty site: in addition to providing Gitweb when you access it via a web browser, it also allows cloning of repositories in the same namespace. So, for example, you can visit http://git.ithinksw.org/ITFoundation.git, and receive a Gitweb-generated interface to the repository, but you can also run git clone http://git.ithinksw.org/ITFoundation.git to clone the repository. tycho is also a fan of Git, and was interested in setting a similar site up for his own repositories, so I've decided to share my configuration here.