As more and more people utilize virtualization for development the need to easily and securely share your work in progress with team members or clients can be a great boost to productivity. Such a tool is also not bad when your kid wants to let his friend access that local minecraft server you are running on your workstation for him, not that I would know anything about that. There are several utilities that are available, and now a plug and play option that is available if you use vagrant.
In recent versions of Vagrant, Hashcorp has added a plugin called Vagrant-share. You can see if its installed by running