Eurekster's swicki search engines look fun and useful.
They claim: "A swicki is new kind of search engine that allows anyone to create deep, focused searches on topics you care about. Unlike other search engines, you and your community have total control over the results and it uses the wisdom of crowds to improve search results. This search engine, or swicki, can be published on your site. Your swicki presents search results that you're interested in, pulls in new relevant information as it is indexed, and organizes everything for you in a neat little customizable widget you can put on your web site or blog, complete with its very own buzz cloud that constantly updates to show you what are hot search terms in your community."
A meta-search for swicki searches here: http://swickihome.eurekster.com/dir.htm?mode=search
And a favorite swicki here:
Vision Thing (transhumanism, etc.): http://vision-thing-swicki.eurekster.com/
The site still has lots of bugs. Very beta, but take it for what it's worth.