XapianFu is a Ruby library for working with Xapian databases. It builds on the GPL licensed Xapian Ruby bindings, but provides an interface more in-line with "The Ruby Way"(tm) and is considerably easier to use. For example, you can work almost entirely with Hash objects, and XapianFu will handle converting the Hash keys into Xapian term prefixes when indexing and when parsing queries. It also handles storing and retrieving hash entries as Xapian::Document values. XapianFu basically gives you a persistent Hash with full text indexing (and ACID transactions).
Arch is an extension of Apache Nutch (a popular, highly scalable general purpose search engine) for intranet search. It includes blind test evaluation tools for comparing to other search engines. Arch has many features critical for corporate environments, such as document level security.
InstaSearch is an Eclipse IDE plug-in for performing quick and advanced searches of source code files. It uses the Apache Lucene library for indexing and fast searching of files in the workspace. The search is performed instantly as you type, and resulting files are displayed in an Eclipse view. Each file then can be previewed using a few of the most closely matching and relevant lines. A double-click on the match leads to the matching line in the file.
FM SiteSearch Pro is a quick and simple solution to adding professional search capability to a Web site. It comes with a relevance engine, control panel, large Web site support, MySQL support (optional), search/keyword statistics, advanced searches, and specialized searches, and is fully customizable. It also comes with a setup interface.
Web Search Script can search the contents of a text file stored on your server by editing the script source code, or the file location can be left blank to allow your users to enter a URL to a text document stored on a remote Web server. Search results will be listed by line number, with contextual information surrounding the search term. Clicking search results will scroll the complete text in the right pane to the result's location in the complete text.