Dictionaries, Italian
DOP Dizionario italiano multimediale e multilingue d'Ortografia e di Pronunzia
Italian Language Dictionary (Garzanti)
Italian Language Dictionary, Italian-English, Spagnolo-Italiano, Francese-Italiano, Tedesco-Italiano (Sansoni, Zanichelli)
Dizionari bab.la : English, Italian, German, French, Arab, Chinese, Korean, Hindi, Japanese, Russian, Spanish, Dutch, Polish, Rumanian, Portuguese, Swedish, Turkish

Dictionaries, English
Cambridge Dictionaries online
Merriam Webster (WWWebster Dictionary)
Slang Dictionaries
OneLook Dictionaries

Dictionaries, Foreign
EUROVOC (thesaurus in all EU languages)
IATE Inter Active Terminology for Europe (translation in all EU languages)
Human Languages Page
French-English [ARTFL Project]
German-English
English-Russian/Russian-English
Italian-English-Italian
Web of On-line Dictionaries
Foreign Language Dictionaries from Yahoo

Encyclopedias
Britannica Online
Smithsonian Encyclopedia

Thesauri
Roget's Thesaurus [version 1.02, supplemented July 1991]
Merriam Webster (WWWebster Thesaurus)
The Astronomy Thesaurus

Quotations
Bartlett's Familiar Quotations, 1901 ed

Biographical Information
World Biographical Index

Writing Resources
A Quick Guide to Citation Styles
Strunk, William, 1918. Elements of Style.
A Guide For Writing Research Papers - MLA
APA Style Resources
Documentation Guide - Chicago / Turabian
The Chicago Manual of Style Online

Virtual Reference Desks
The Internet Public Library
Yahoo [Reference]
Alfred University
Cornell University
Middle Tennessee State University - Quick Reference
Purdue University Libraries
University of Texas/Austin
Internet Public Library
Martindale's The Reference Desk
My Virtual Reference Desk