When I was at Oracle, we hade a modified version of RCS which we called NETRCS. It basically worked the same as RCS, except we could set an environment variable to point to the hostname and path of the repository:
(NETRCS=hostname:/dir1/dir2/dir3 ; export NETRCS)
Obviously, we had had serveral NETRCS servers, each having sources for different projects.
Does anyone know where I might find something similar? Someone pointed me to CVS - unfortunately that didn't do what I needed.