(cross-posted from Enterprise Search Blog)
Are you trying to think of ways to make your Search Server site more interactive and graphical? You can use Federation as a way to enhance the functionality of your search result pages.
The Federated Search Web Part makes it possible to display more than results from OpenSearch (1.0/1.1) sites on your search results page. The Search Server 2008 SDK explains how to include results from SQL Server database queries and search sites that do not expose XML feeds (such as Atom or RSS). In both scenarios, you do this by means of a "connector," a light-weight interface that sends queries to a given location or database, places the results into a structured XML document, and sends that XML to a Federated Search Web Part.
This sample is part of the Search Community Toolkit.