Quotations (Bartleby.com)
Includes several familiar sources, such as Bartlett's Familiar Quotations, 10th ed.

Creative Quotations
This searchable database of more than 25,000 quotations from 2,800 people cites the source of each quotation. The quotations can also be brought up by month and day. There are also Indexes: by last name, day of birth, profession, women by profession, and women by day of birth; Themes: holidays, seasons, events; and Special Collections: Benjamin Franklin, Ralph Waldo Emerson, Cicero, Aristotle, Thoreau, George Eliot, Martin Luther King, Jr., Mark Twain, Shakespeare, Gandhi, Emily Dickinson, Dorothy Parker, and Ambrose Bierce.

Simpson's Contemporary Quotations
Provides over 10,000 quotes from over 4000 sources, including 25 categories of quotes, and 60 sections.

The Quotations Archive

The Quotations Page
Originally developed as a catalog of quotation resources on the Internet, the site has since evolved into a large-scale quotation site with many original resources.