LIBRARY: Reference Directories

Bartleby.com: Search across an amazing selection of dictionaries, thesauri, quotation books, encyclopedias and other reference works.

Infoplease.com: Well organized and comprehensive group of reference materials including an almanac, atlas, dictionary encyclopedia.

Refdesk.com:  A great source for facts, news and other reference assistance.

Yahoo.com Reference: Reference materials broken down into forty different calories from acronyms to time.