epaze

IntraSITE Search is a new, free utility capable of searching static websites on servers where no database has been set up. It has all the functionality of Google Site Search, but there are no ads, and it’s completely free.

Sphider is a lightweight web spider and search engine written in PHP, using MySQL as its back end database. It is a great tool for adding search functionality to your web site or building your custom search engine.

PhpDig is a web spider and search engine written in PHP, using a MySQL database and flat file support. PhpDig builds a glossary with words found in indexed pages. On a search query, it displays a result page containing the search keys.