Coofer Cat's got a search facility. This time it's a proper indexing search engine that looks into non-HTML files, and indexes the whole site - as opposed to the old GM script that did a simple grep of the .html files in the archive directories. There are loads more features too...
Incidentally, the search facility is provided by a forthcoming PreEmptive product. It's an appliance based, low cost of ownership search engine. It's specifically designed to have minimal maintenance overhead, yet have numerous useful features to make your life easier.
From a searching perspective, there are numerous ways the results can be presented. Naturally, the HTML output is completely customisable by powerful (and fast!) templates, or by XML/XSL. The order of the results can be adjusted as well. Five settings between "relevance only" to "linkage only" are provided for flexibility. "Linkage" is a bit like Google's PageRank, in that it's a measure of how many links point to a page, with respect to all other pages, and thus could be considered a measurement of the "importance" of a page.
For Webmasters, there are a number of other features which are really useful. First of all, an integrated link checker can tell you which pages have broken links on them. Additionally, an automatic site mapper can create a sitemap for you, which is updated each time the search engine visits your site. If that's not enough, you can check the W3C validity of pages with the integrated checker (the results of which can be included in search results too).
All in all, it's pretty damn impressive. But then I would say that, because I put it together ;-)