Clusty the Clustering Engine is a meta-search engine which uses VivÌsimo which is based on technology from Carnegie Mellon. Clusty does a nice job of clustering results from multiple search engines into folders that actually make sense. There are some other neat interface issues that Google could learn from.
They do the clustering by crawling and running some sort of cluster processing on the information. I’m not sure how this works over the engines, though it makes sense over a domain. VivÌsimo also offers enterprise solutions – I wonder if they could be adapted to crawl and cluster humanities texts?
One of the neat things is that you can now get a Dashboard widget for Clusty.