General Reference

Biography.com: Companion site to A&E's "Biography" TV series: Search database of about 25,000 biographies. Includes a Born on this Day feature, a listing of top 10 bios, discussion forums, and a Classroom section for students and teachers.
HowStuffWorks: Explains how things work in various fields. Illustrated. Handy source of details for writers.
iTools: "Quick access to the best Internet tools." Search capabilities in the areas such as Language, Research, Finances, Maps, Internet, and People.
Martindale's: The Reference Desk: A wide variety of Internet research tools, literary and otherwise.
Refdesk.com: "The single best source for facts on the Net." Indexes a wide variety of quality Internet sites and makes it easy to access the information.
Research It: Language, Library, Geographical, Finanacial, Shipping, and Internet research tools.
World Factbook: Provides extensive information on countries, territories, and dependencies thoughout the world, gathered and maintained primarily by the CIA for the use of government officials and governing bodies. All material here is in the public domain.