For some which are interesting in research, or managing their files better, I found that organizing files in tree structure isn't the best choice.

does anyone know about a windows application which will allow me to organize/find/manage my files using tags, keywords, descriptions?

I remember that I've seen something similar for organizing movies or audio files. Do you know something similar for organizing document files. I also know that was something similar for books review and management. Do you know about a review of such type of applications?