The idea is simple — Upload a CSS file and Surplus will parse out the classes and ids. Then, give it a URL to crawl and it will generate a list of selectors that appear to be unused. I'm currently working on a feature that will index files within specific "images" directory and, similarly, generate a list of potentially unused image files. It's a quick and easy way to find and remove clutter from your server and even from within your code.
Tools: Photoshop, HTML, CSS, PHP, MySQL