focuseek searchbox is a family of easily installable full-text search engines that can spider Internet and intranet data sources (Web sites, newsgroups, FTP sites, and others) or index data you feed to it and make it available for searching. It supports a variety of input formats (among them HTML, PDF, Microsoft Word DOC, and RTF), and is easily scriptable via SOAP and extendable through plugins. It can scale to millions of documents and comes with a full-fledged GUI client, a built in Web search portal, and an RSS server.
Xapian is a search engine library, scalable to collections containing hundreds of millions of documents. It's written in C++ with bindings for Perl, Python, PHP, Java, Tcl, C#, Ruby, and Lua. It is a highly adaptable toolkit that allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model and also a rich set of boolean query operators. Omega is a Web search application built upon the Xapian library. It can index a Web server's document tree (including HTML, PDF, OpenOffice, MS Word/Excel/Powerpoint/Works, WordPerfect, RTF, PS, etc.), or data exported from arbitrary sources (e.g. SQL databases).
FYM is a media organizer that performs quick scans for media files (more than one hundred thousand media files in less than a minute). With its search engine, you easily find and open music, photos, videos, books, and other data types you determine. Covers of music folders and photo albums can be shown. It has strong random functionality.