Adds icons for menu links.
You can create your own icon-pack too.
Copy a folder in modules/icons/icons/iconpacks/ and start replacing the image files to create your own icon pack.
You can add, edit and delete icons. Go to the modules/icons/iconpacks/YOUR IMAGE PACK/icons.css file and define the new icons. You can find the class name of the items at the source code or by using the Firefox extension Firebug