You can't actually search the databases, but you can pinpoint just the databases you need. Direct Search , compiled by Gary Price of George Washington University, is a great resource for databases and for more information on the invisible Web. With ProFusion you can search more than 1,000 information sources, including the invisible Web. It's in beta test, but you're welcome to try it. ProFusion works by formatting your search criteria to meet the specific requirements of each data source.
ProFusion features Automatically searches across multiple sources and categorizes the results.
Suggests alternate searches based on information it has learned. Allows searches by category, or by source within a category. You can automate searches and enable alerts when search results change. Does not require specialized search skills. More on the Invisible Web.