stegfs is a Fuse based file system which provides absolute security. Using encryption to secure files, and the art of steganography to hide them, stegfs aims to ensure that the existence of such files isn't guaranteed. Implemented as a Fuse based file system and using the mhash and mcrypt libraries to provide the cryptographic hash and symmetric block cipher functions, stegfs is at the cutting edge of secure file system technology.
Weed-FS is a simple and highly scalable distributed file system. There are two objectives: to store billions of files, and to serve the files fast! Instead of supporting full POSIX file system semantics, it implements only a key-file mapping. Instead of managing all file metadata in a central master, it manages file volumes in the central master and lets volume servers manage files and the metadata. This relieves concurrency pressure from the central master and spreads file metadata into volume servers' memories, allowing faster file access with just one disk read operation. It is modelled on Facebook's Haystack design paper. Only 40 bytes of disk storage are required for each file's metadata, and disk reads are O(1).
TOCC is a Tool for Obsessive Compulsive Classifiers. It implements a file system that uses tags instead of folders, allowing you to classify files however you want. For example, you could tag photos by location, people, and technique (e.g. black & white, HDR). Finding files is as simple as running a query like "give me all files tagged photo and my-love".