It allows you to easily search your entire filesystem directly from Unity Dash
The Ubuntu Filesystem Tree Lens is an Unity Lens that enables users to easily and quickly find files and folder in their filesystem, directly from Unity Dash.When you click a folder, Nautilus will open it showing you the contents. When you click a file, it will be opened in an app that can view the respective file.
To install the Unity Filesystem Tree Lens plugin in your Ubuntu operating system, open a terminal window (hit the CTRL+ALT+T key combination) and paste the following commands (one by one, hitting Enter after each one):
sudo add-apt-repository ppa:jesse-imaginaryrobots/ppa
sudo apt-get update && sudo apt-get -y install fstree
You will need to restart your session after the installation. This Lens is available only for the Ubuntu 12.10 (Quantal Quetzal) operating systems.