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.
PhotoFS is a Web-based photo album or image gallery, based on the files-as-directories and attributes-as-files concepts at the core of the ReiserFS 4 filesystem. It does not require ReiserFS 4, but is much more efficient on that system than on others. It does many of the same things as other Web galleries, at least as far as the basics go. What makes it different is its use of the filesystem instead of a database. It allows you to use regular unix tools to access your photo collection. It can handle very large collections, and also encourages multiple categories per file, deep category hierarchies, and batch processing.