A nautilus script is just an executable shell script (usually bash) that is placed in a special scripts directory so that the Nautilus graphical shell can find it. This is a really neat function of Nautilus, because it allows you to extend the functionality of the file browser to do just about anything.
To install a Nautilus script download and unpack it (if needed), then click on it with your right mouse button and select Properties. Now click on the Permissions tab and mark Allow executing file as a program when done hit the Close button. Sometimes a script can look like this when you download it, all you have to do is copy and paste the text into a new text document. Then save it and make the file executable. When the file is executable cut and paste it into your scripts folder, to do this right click the Nautilus script and select cut. Now open your Home folder (Places -> Home) and press Ctrl+H this will show your hidden folders. Open the .gnome2 folder and then the nautilus-scripts folder and paste the Nautilus script in the folder. For a script to appear on the script menu, it must be placed in your scripts directory and be executable. If you place an executable script in your scripts directory, its name will not necessarily appear on the scripts menu immediately. You first must visit the scripts directory with Nautilus.To do this right click in the nautilus-scripts folder and select Scripts followed by Open Scripts Folder. Once the directory is visited, Nautilus will know about which scripts you have, and you will be able to use them. Scripts are invoked by selecting a file or group of files, and right-clicking with the mouse, to bring up a ‘Context’ menu. One of the options of this menu is the ‘Scripts’ submenu, which allows you to select a script to invoke on the selected files.
Some useful scripts:
XML animated background creator 0.6
This script automatically creates a wallpaper .xml with images from the folder in which you run the script.
mount and unmount ISO images
Mount and Unmout ISO images without burning them
opens a root-enabled instance of a nautilus window in selected location. requires sudo priviledges and gksudo, which may involve security risks.