Although what I'm about to talk about is well documented, I've never come across it in my 10 year career using Git. I stumbled across it out of sheer curiosity to see what would happen if I used a repository instead of a remote name. In theory Git would treat them the same, since everything is technically a ref, and it did. The idea is simply to be able to push your code anywhere, without having to first add the remote to your local repository. You're probably asking why you would want to do this, or why anyone would even care that this is possible. I have a few use cases below which are now way easier day to day.
Did you know you can also create symlinks using PHP? Now when you have a lot of files you want to symlink in bulk, such as Apache project files which I described in a previous Blog post, you can simply create a php file to do all the work for you.