This is taken from here.
http://stackoverflow.com/questions/67699/how-do-i-clone-all-remote-branches-with-git/72156#72156
Want this as a gist because I always come back to this posting.  

First, clone a remote git repository and cd into it:

    $ git clone git://example.com/myproject
    $ cd myproject

Next, look at the local branches in your repository:

    $ git branch
    * master

But there are other branches hiding in your repository! You can see these using the `-a` flag:

    $ git branch -a
    * master
      origin/HEAD
      origin/master
      origin/v1.0-stable
      origin/experimental

If you already have a existing repository but there is a new branch that is yet listed do a:  

    git fetch

If you just want to take a quick peek at an upstream branch, you can check it out directly:

    $ git checkout origin/experimental

But if you want to work on that branch, you'll need to create a local tracking branch:

    $ git checkout -b experimental origin/experimental

Now, if you look at your local branches, this is what you'll see:

    $ git branch
      master
    * experimental

You can actually track more than one remote repository using `git remote`.

    $ git remote add win32 git://example.com/users/joe/myproject-win32-port
    $ git branch -a
    * master
      origin/HEAD
      origin/master
      origin/v1.0-stable
      origin/experimental
      win32/master
      win32/new-widgets

At this point, things are getting pretty crazy, so run `gitk` to see what's going on:

    $ gitk --all &