BeIndexed searches all your files and builds a database with their content. You can then search for files by content, like on Google etc.

"Why would you want to use something like this, queries already does this right?"

Actually they don't, queries can only find files based on their attributes like their name, type and size. It can't find files based on their content, which is exactly what BeIndexed does. BeIndexed can also be expanded to search for attributes as well, combining the best of both worlds, but even at this stage it can be pretty handy.