TagSpaces lets you organize, tag, and browse your files, photos, and documents on many platforms. It lets you create and manage notes and Web snippets (like in Evernote, but completely offline) and create a personal Wiki system. It features integrated MHTML, PDF, ODF, and image viewers, a Markdown viewer and editor, an advanced WYSIWYG HTML5 editor, file tagging based on filenames (extremely portable), a simple source code viewer and editor for the most common programming languages, and basic file and directory management.
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".
phpilelist is a file listing script that you can upload to a directory on your Web server. There's just one file to upload, and the script will list all files with extensions you specify and make them available for download. If you add, remove, or rename files, the listing will automatically update. If the directory contains a file named 'readme.txt', the script will show this file's contents above the download links.
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.