Ready Reference: Quotations

Bartlett's Familiar Quotations: The Ninth Edition (1901) of John Bartlett's famous collection of quotations; part of Columbia University's Bartleby Project.
Columbia World of Quotations: From Project Bartleby. 65,000 quotations from 5000 authors .
Creative Quotations: 50,000 quotations. Search by keyword, source, topic, author.
A Dictionary of Scientific Quotations: Memorable quotes from the scientific community.
Quoteland: Includes quotations by topic, literary quotations, humorous quotations.
Respectfully Quoted: A Dictionary of Quotations. 1989: From Project Bartleby. A dictionary of quotations requested by the Congressional Research Service.
Simpson's Contemporary Quotations: From Project Bartleby. The most notable 10,000 quotations, 1950-1988.
Yahoo! Reference: Quotations: Yahoo!'s searchable subject guide to quotations, with links to other quotation resources.