A wide perspective is required for all, in general ;-) . General Knowledge is very essential for developing a wide perspective. This gives an ability to recognize, appreciate and adapt to ideas, concepts, methods and innovation when they happen.

• Wikipedia - Multilingual free-content encyclopedia
• Word Web Online
• TheFreeDictionary
• Knowledge@Wharton
• Liam's Pictures from Old Books
• Infoplease - comprehensive encyclopedia, almanac, atlas, dictionary
• Penn Libraries
• Internet Public Library
• Internet Archive
• University of Virginia Library
• Internet Library of Early Journals
• ThinkQuest Library