From http://stackoverflow.com/questions/67699/how-do-i-clone-all-remote-branches-with-git

git-branch

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   
remotes/origin/HEAD   
remotes/origin/master   
remotes/origin/v1.0-stable   
remotes/origin/experimental 

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 
  * experimental  
  master 

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   
remotes/origin/HEAD   
remotes/origin/master   
remotes/origin/v1.0-stable   
remotes/origin/experimental   
remotes/win32/master   
remotes/win32/new-widgets

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