greeneagle, I hope I am not the only one to answer you, but I have seen three scripting methods of adding a site search, all free - no advertising on some.
There are
2 server side options: PHP and cgi/PERL. This can mean using a data base to store the index - PHP uses SQL and ODBC that I know of, and probably ASP as well. Some scripts just create .txt or .dat files for their index and are probably less involved.
There is
a client side approach as well that involves using javascript. It runs on the clients computer and I would definetly not recommend this for any large site.
Here is a perl script system:
http://perlfect.com/freescripts/search/
Here is a PHP system:
http://sourceforge.net/projects/autoindex/
Both of these are GPL (Gnu Public Licence) and will not have advertising.
Neither needs a database server component, and they both look to have great support and are highly configureable.
I am just getting to the point in the next week of installing one (or more! if necessary) of these to my site.
THEREFORE, I have
NO experience using these search scripts whatsoever, but I do find installing most PHP and PERL to be relatively straightforward - that is why I chose these. They look like I can handle them!
I do not feel comfortable making very many recommendations in this area (of serverside scripts), but it is a start and hopefully someone with some brains, like ronniethedodger will come to the rescue.
I should also butter up redcircle and paulhiles as ones I think are quite knowledgeable and helpful as well. LOL