Tara (Research Buzz) is just terrific. See her posting today on keyword-specific RSS feeds from headlinenews.com. This type of feature is also available from FindForward (formulate a query and choose “Get RSS” from the drop-down menu, and you will be provided with a url to enter into your aggregator), and Topix.net (after you have generated your search query, scroll down to the orange XML icon on the left hand side of the page to obtain the url for your aggregator).