"If desktop search tools like Kat and Beagle are overkill for
your needs, then try Docco, a little application designed
specifically to index documents and search inside them.
"Docco is based on Apache's indexing and search engine Lucene,
and it requires a Java Runtime Environment (available free of
charge at www.java.com). To install Docco, download the latest
version of the software, unpack it, and move the resulting
directory to the desired location..."