Add FTP'd files to Media Library without moving them to upload folder?

I have uploaded many files via FTP and have organized them into logical folders and subfolders that I would very much like to keep. However, it would be incredibly convenient if I could add these files to my posts using the Media Library rather than tracking down the appropriate URLs every time I need to use them. Is there a plugin that will add files to the Media Library from my server without copying those files to the uploads folder (and consequently throw over up my pretty, logical folder structure)?