Beyond Google and Yahoo: New, Nifty Search Engines to Optimize Your Research http://www.llrx.com/features/supersearch.pdf, LLRX (April 2006)
Barbara Fullerton and Sabrina I. Pacifici at LLRX recommend several specialty sites and vertical search engines for more focused searches. This is a pdf file (21 pages) and seems comprised mainly of screenshots. There are many good sites for scientific materials (Scirus, SciSeek, Public Library of Science, and EEVL), Health (PubMed, Medscape, Omni), US Government, News (Topix, Newsdirectory) and some specialty search such as Blogpulse, Podzinger, and Blinkx. There is much more - browse and try.
have put up this presentation about specialty sites and search engines recommendations focus on subject area and issue-centric sites to facilitate obtaining search results that are better targeted to the scope of your requests. Whether you are looking for government data, blogs, RSS feeds, videos, podcasts, news or scientific papers, this guide will serve you well.