Permissions are a pest.
Basically, you need to make sure that all of those developers can write to everything in the git repo.
Skip down to The New-Wave Solution for the superior method of granting a group of developers write capability.
The Standard Solution
If you put all the developers in a specially-created group, you can, in principle, just do:
chgrp -R <whatever group> gitrepo
chmod -R g+swX gitrepo
Then change the umask for the users to 002, so that new files get created with group-writable permissions.
The problems with this are legion; if you’re on a distro that assumes a umask of 022 (such as having a common users group that includes everyone by default), this can open up security problems elsewhere. And sooner or later, something is going to screw up your carefully crafted permissions scheme, putting the repo out of action until you get root access and fix it up (i.e., re-running the above commands).
The New-Wave Solution
A superior solution—though less well understood, and which requires a bit more OS/tool support—is to use POSIX extended attributes. I’ve only come to this area fairly recently, so my knowledge here isn’t as hot as it could be. But basically, an extended ACL is the ability to set permissions on more than just the 3 default slots (user/group/other).
So once again, create your group, then run:
setfacl -R -m g:<whatever group>:rwX gitrepo
find gitrepo -type d | xargs setfacl -R -m d:g:<whatever group>:rwX
This sets up the extended ACL for the group so that the group members can read/write/access whatever files are already there (the first line); then, also tell all existing directories that new files should have this same ACL applied (the second line).
Hope that gets you on your way.
These days there is a "smart HTTP" upload feature, might even supersede the SSH access. No more private key generating is required, and installing should be easier, because the server component can be written in any language of choice:
If all fails, you can also choose to setup an Apache server, and use the standard git-http-backend CGI binary, see: What are the steps to setup git-http-backend w/ Apache on Windows?
Best Answer
I use Gitorious on my Ubuntu server to manage all my personal projects. It's quite a lot of work to set up, but well worth it in my opinion.
You could also sign up for a free account on Gitorious itself, or the well-known (but unstable in my experience) Github.