You can easily use the Google Search Engine (and others as well) to find gigabytes of Mp3s, Ebooks, Images and Movies that most people will never find.
To find those files you need an advanced understanding of the Google Search possiblities, here are some basic examples on what you can find and explain them. From there its up to you to enhance this searches.
What we are looking for are directories that have been indexed by google and don´t have a file in them that is loaded when loading the directory in your browser.
If you want to lock a directory you simply put a basic index.htm(l) file into it and this file will be loaded when you try to open the directory and the content that is also in the directory will not be displayed.
That means we will have to exclude index.htm and index.html files from our search to find only open directories. (As a sidenote, there are of course other means of protecting directories like .htaccess files)
To exclude something from your search you use the “-” operator in the search field. We want to make sure that no webpages are displayed that have “htm” or “html” in their url, remember, we only want the directories.