Bartleby: The reference bookshelf. It contains some of the best dictionaries, encyclopedias, quote and verse references, grammar/style references and classical literature (Harvard's Classics.) Many reference sites now charge but this is one of the best and still free. Should be on everyone's shortcut bar.
Wikipedia: " the free encyclopedia that anyone can edit" This description doesn't do it justice. Wiki is a phenomenal resource that everyone should get in the habit of using.
Free Translation.com Babblefish
FirstGov: United States central site for all things governmental. If you are looking for information about or provided by a governmental organization then this is your first stop. Why is it here instead of under 'politics?' Because it's more of a research tool for information and services provided by the government then a political commentary site.
Biography.com: has an extensive searchable database with cross listings of biography and history channels.
AllExperts: A co-site of About.com, "the oldest & largest free Q&A service on the Internet." Broken down in categories, it offers a place to send a question to someone and hopefully get an answer. I've not tried out this nor do I know what criteria they use to judge experts, but hey.. it's free.
About.com: "practical advice and solutions for every day life" In 2005 About, Inc. was acquired by The New York Times. It is a great resource on pretty much any topic you could think of and a first stop.
How Stuff Works: has subcategories for science, entertainment, electronics, auto, computer, home, money, travel, etc.. An interesting conglomeration of information.
dmoz: " The Open Directory Project is the largest, most comprehensive human-edited directory of the Web. It is constructed and maintained by a vast, global community of volunteer editors."