Simple www and 7393 search function:
All the bells and whistles: Google Advanced Search
Yellow/White pages, reverse lookups: Whitepages
Maps
Maps, directions, satellite & hybrids: Google Maps
Been around a long time, now owned by AOL: Mapquest
Includes Yellow/White pages: Maps On Us
Miscellaneous
Convert units on the fly: OnLineConversion.com
Dictionary/Thesaurus: Dictionary.com
Open Source Encyclopedia: Wikipedia
If all else fails: The Internet Public Library