Google Scholar - Google Scholar enables you to search specifically for scholarly literature, including peer-reviewed papers, theses, books, preprints, abstracts and technical reports from all broad areas of research. Use Google Scholar to find articles from a wide variety of academic publishers, professional societies, preprint repositories and universities, as well as scholarly articles available across the web.
Google Print - Google has partnered with several libraries and publishers to digitize their collection and 'Google Print' aims to search the book content and links to view the entirety of public domain books or, for books under copyright, just a few pages or in some cases, only the title's bibliographic data.
Google News - Google News gathers stories from more than 4,500 news sources in English worldwide, and automatically arranges them to present the most relevant news first and also allows customization.
Scirus - Searches science-specific web pages as well as some science journals. The advanced search allows you to limit your search to specific information types (conference proceedings, patents, scientists' homepages, etc) or by subject areas.
MatWeb - is a searchable database of material data sheets, including property information on thermoplastic and thermoset polymers such as ABS, nylon, polycarbonate, polyester, polyethylene and polypropylene; metals such as aluminum, cobalt, copper, lead, magnesium, nickel, steel, superalloys, titanium and zinc alloys; ceramics; plus semiconductors, fibers, and other engineering materials.
GLOBALSPEC, The Engineering Search Engine - A search engine to find engineering related websites, part numbers, application notes, materials properties, patents, standards & products and manufacturers.

Directories

Librarians' Index to the Internet - offers a searchable, browsable collection of over 16,000 high-quality Websites, and a weekly newsletter, available by email or RSS, of high-quality Websites.
Open Directory Project - is the largest, most comprehensive human-edited directory of the Web.
EEVL - is the Internet Guide to Engineering, Mathematics and Computing. EEVL's mission is to provide access to quality networked engineering, mathematics and computing resources
Science Research Portal - allows access to numerous scientific journals and public science databases.