If you have not seen Grokker, you should. It is a very interesting and useful information visualization tool that can be used for federated search. Some call it a research platform. At Internet Librarian in October, the CEO of Groxis, said that Grokker "clusters documents and categorizes them on the fly to make sure that users get the information they are looking for." Christy Higgins of the Sun Microsystems Library talked about how they are using the product. According to notes from her session, "engineers [at Sun] are visual learners and are making widespread use of the system." The Sun case study can be viewed here.
Having seen demonstrations of Grokker, I would considering testing it as a federated front end to several repositories of digitized materials as well as using it in a digital library setting. The visual nature of the product definitely gives us something that we're missing in our search engines (as well as something that others have tried and failed at).
Technorati tags: Digitization, Digital libraries, Federated search