Aphorisms Galore!
http://www.ag.wastholm.net
Aphorisms and their origins, searchable by categories and author.
Bartlett’s Familiar Quotations
http://www.bartleby.com/100/
Old favorite (1919, 10th edition), with passages, phrases, and proverbs traced
to their sources.
Columbia World of Quotations
http://www.bartleby.com/66/
65,000 quotations by more than 5,000 authors in 6,500 subjects.
Creative Quotations
http://www.creativequotations.com
Sorted in different categories, although the keywork search could be tricky.
The Quotations Page
http://www.quotationspage.com
Features quotes collected by author and subject, with discussion forums.
Quoteland
http://www.quoteland.com
Large, searchable collection with a User Discussion Group to exchange help.
A Short Dictionary of Scientific Quotations
http://naturalscience.com/dsqhome.html
Short, some quotes are very long.
