CGILua is a tool for developing dynamic HTML pages and manipulating input data from forms. It uses the interpreted language Lua for codifying its scripts. It has been on the road for almost 8 years now, being used in many Web products and sites. It is extensible through Lua libraries and dynamic loading of C/C++ libraries. Scripts can be written as Lua programs or HTML templates (HTML with Lua code embedded). Scripts are platform-independent.
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).