TAGXFS!

TMSU is a tool for tagging your files. It provides a simple command-line tool for applying tags and a virtual filesystem so that you can get a tag-based view of your files from within any other program.

tagfs is Fuse file system to organize your files using tags.

Dantalian is a set of Python scripts to help with file organization and tagging with hard links.

Makes the benefits of tagging available through a traditional filesystem framework like VFS.

Tagsistant is a semantic filesystem for Linux and BSD kernels. Its tag based method to organize files let's you quickly search and find it. It's able to reason on tags, it allows the creation of external plugins to enhance its behavior and its Free Software!