Mac OS X 10.4 Server includes an Apache module called “mod_spotlight_apple”. This module allows (obviously enough) searching your webserver via spotlight. More information is available here:
http://images.apple.com/server/pdfs/Web_Technologies_Admin_v10.4.pdf
The gist of it enabling it is:
Enable mod_spotlight_apple using the Web section of the Server Admin tool. Then browse http://<yourserver>/.spotlight to see the rather primitive search screen.

Of course based on the above screenshot you can see I’m having trouble getting mod_spotlight_apple to find anything…
Update: As pointed out in the comments to this post Apple has posted an article on how to set up mod_spotlight_apple: http://docs.info.apple.com/article.html?artnum=302424
