Tagsistant is a semantic filesystem for Linux and BSD kernels. It uses directories as tags and allows file tagging by simply putting files inside desired tag directories. The path you are walking by is your query, e.g. tagsistant/tag1/AND/tag2/OR/tag3/AND/tag2/. Being a low level interface, a filesystem can be instantly used by shell users, file managers, or CGI. A plug-in architecture is under development to add autotagging functionality for common files like .mp3, .ogg, .jpeg, .html, and .xml. A transparent ontology engine is also under development to allow users create a relationship schema between directories.
movemetafs is a searchable filesystem metadata store for Linux that lets users tag local files (including image, video, audio, and text files) by simply moving the files to a special folder using any file manager. It also lets users find files by tags using a boolean search query. The original files (and their names) are kept intact. movemetafs doesn't have its own user interface, but it is usable with any file manager.
Red-Piranha is a search system that can actually learn what you are looking for. It can be used as a Web page, command line, or XML-WebService, so it will work with most languages, including Java, Perl, C#/.NET, and PHP. It includes learning abilities for the Desktop/Internet search functionality. All feedback from the user is stored in (editable) XML and RDF, and is used by the system to improve the quality of searches.
Doodle is a desktop search engine for Linux. It searches your hard drive for files using pattern matching on meta-data. It extracts file-format specific meta-data using libextractor and builds a suffix tree to index the files. The index can then be searched rapidly. It is similar to locate, but can take advantage of information such as ID3 tags. It is possible to do full-text indexing using the appropriate libextractor plugins. It also supports using FAM to keep the database up-to-date.
The OMCSNet-WordNet project aims to improve the quality of the OMCSNet dataset by using automated processes to map WordNet synonym sets to OMCSNet concepts and import additional semantic linkage data from WordNet. It is based on OMCSNet 1.2, a semantic network and inference toolkit written in Python/Java. OMCSNet currently contains over 280,000 separate pieces of common sense information extracted from the raw OMCS dataset. This project is also based on WordNet, an online lexical reference system that in recent years has become a popular tool for AI researchers.
mod_musicindex is an Apache module aimed at being a C alternative to the Perl module Apache::MP3. It allows nice displaying of directories containing MP3, Ogg Vorbis, FLAC, or MP4/AAC files, including sorting them on various fields, streaming/downloading them, constructing playlists, and searching. It also provides features such as RSS and Podcast feeds, multiple CSS support, and archive downloads.
xSiteable is a complete all-you-need package for creating sites that are fully relational, open source, fully templating-enabled, using only XML-based technologies to help you create complex sites on the fly. It packs such features as topic maps, notation for content, and the fast Sablotron xslt parser.