I am quite keen on the google coop - partly because it's for a work project based on mediawiki, and our main audience is utterly confounded by any search engine that doesn't function like google, sigh. I've put it on our main organisation website, but couldn't get the extension to work for mediawiki, despite following all the instructions, dammit!

If you have any ideas of how to tweak and play around with the existing mediawiki search, though, I'd welcome them.

♥