WaldScan is a PHP class which recursively scans a given directory for a list of selected file types. It has many uses for any Web page which serves files over HTTP/HTTPS, for a CLI program which does batch processing of files, or in cron jobs for caching file data for faster access.
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".