General Reference Portals
refdesk – Great place to find all types of reference materials ,and other information.
InfoPlease – Excellent site for references especially encyclopedias.
Library Spot – very good site for references and other resources such as top books.
Merriam-webster – Very good site that includes thesauras and Spanish/English.
YourDictionary – Very easy to use with lots of resources.
Dictionary.com – Very simple and easy to use.
Encyclopedia.com – great site and very easy to use.
Wolfram Mathworld – Excellent Math Encyclopedia.
Eh Net – Economic and Business encyclopedia.
Science Encyclopedia – very good science encyclopedia.
CIA World Factbook – most up to date and complete almanac.
50 States – Good for studying the U.S. states.
World Atlas – Good for studying the world.
National Atlas – Very specific maps available on the site.
University of Texas Map Collection – Most complete online map collection available.
Conversion & Special
Online Conversion – Convert all kinds of measurements.
XE – Currency Converter
Quoteland – Quotes on every major subject.
On This Day – Find out what major events happend on each day of the year.