I am dual booting Windows 7 and Fedora with a shared storage partition. In Windows 7 I've adjusted my libraries to point to the shared storage partition. I'd like to do the same for Fedora, so by default my /home/username will always display the contents of my shared storage and nautilus will show it in the file browser window.
You could just edit /etc/passwd to update the home directory, but this may cause issues.
In this example you need to change the /home/test to point to your shared location/
You don't say what filesystem type you are using for your shared filesystem, but I'll assume it's going to be FAT32 as it's probably the easiest to mount on both Linux and Windows.
FAT32 does not support the same level of permissions (user,group,all) as native unix filesystem types and this may lead to problems with for example things like SSH which insists on the .ssh directory having very restrictive permissions so only that single user can read it.
You can do:
mv /home/username/* LOCATION_OF_SHARED_STORAGE ln -sf LOCATION_OF_SHARED_STORAGE /home/username
But as hardlib notes in his answer, this might not be a really good idea, because the shared partition will not support the full set of UNIX permissions if it is FAT32 or NTFS. Instead, it might be better to do:
ln -s /home/username/Documents LOCATION_OF_SHARED_STORAGE
to have the shared storage as a subdirectory of your home directory.