Mercurial (Hg) has an extension called schemes which is very useful when you're working with a server that hosts all of your repositories and you want to point them at a different server or local directory when you're offline.
Does Git have an equivalent?
I'm interested in this for use with Git submodules. Ideally, I would like to cache all of the repositories on my disk and point a different machine's frech clone to my local repos.