Having a small, SEO-friendly corporate site behind a basic password protection scheme, I'd like to add a basic search facility by using one of the off-the-shelf solutions. (I don't mind Google, or Yahoo having the site's content, as long as it doesn't leak to the web).
Google doesn't seem to support this, so I'd like to ask the SO community for recommendations, and pros/cons of each (preferably free) solution? (Rolling my own is the least prefered solution)
Wikipedia has a nice list of Enterprise Search Vendors which links to information about each of them. It's a bit difficult to recommend certain ones without knowing what breadth of features you are looking for past text indexing.
Xapian is one of the free solutions that is readily availible to integrate with your existing applications in several languages, they also have Omega which is a packaged search solution.
If you can run PHP on your site, Wrensoft's Zoom Search Engine is pretty good. It's free for sites under 50 pages, and cheap for larger sites. I use it for my site at http://entrian.com/source-search/ if you want to see it in action. (I'm not affiliated with Wrensoft - just a happy user.)