We have been working with a client who has a Google Search Box installed in their website. http://www.google.com/enterprise/search/index.html

The guys lucky enough to have been working with this technology are loving it. Digging deep into XSLT - we think we have provided one of the strongest search solutions available on the internet (for an internal search engine).

Stay posted - this isn't live yet.

In the meantime, anyone contemplating adding a search tool to their website should be looking at this. It's enterprise level, so not cheap, but you get what you pay for. And this is awesome!