A bit more on hosting git repositories:

I first tried to simply go with a shared directory on a server, i.e. a directory owned by a specific unix group, the group sticky bit switched on, and all users who are supposed to have access to the repository in that group. This works to some degree, but has some drawbacks as git does not auto-magically handle file permissions correctly. So on a system using a umask of 022 (which I guess is a majority of systems?), newly created files are not writable by the group, only by the user who created the files.

So I decided to go with gitosis, which not only eliminates the file permission problem, but is also a more flexible solution as it doesn't require an actual system user for everyone who is supposed to have access to your git repositories. Instead it relies on your user's ssh keys for authentication plus an ACL to determine read/write access to repositories.

There is already a good setup manual, so I won't repeat everything here. On a server running Debian Etch, it boils down to the following commands (make sure you have the backports repository installed):

# apt-get -t etch-backports install gitosis
# sudo -H -u gitosis gitosis-init < YOUR_PUBLIC_SSH_KEY

That is the setup work required on the server. Then you can clone gitosis' admin repository on your local system:

$ git clone gitosis@YOUR_SERVER_HOSTNAME:gitosis-admin.git

I'll again refer you to the setup manual on how to configure gitosis. Just one thing I stumbled over: When adding new users, make sure that you name the key files correctly. I forgot the .pub extension, and wondered why those users didn't get access...