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).
FXL Template an easy to use template engine offering all the basic features of a template system. It supports simple text/array assignments, blocks, and nested blocks. Well-used regular expressions and the simple template syntax are responsible for quick template processing. The template markup is quite easy to learn, even for those not into programming. A Memcache extension for high traffic pages is freely available.