tools  general / financial / geographic / maps / mathematics

General

Financial

• Lease or Buy Calculator (bloomberg.com)
• Mortgage Calculator (bloomberg.com)

• Public Debt to the Penny : The public debt for the current month, and recent months and years.

• Historical Debt (Yearly) : 1950-2000 | 1900-1949 | 1850-1899 | 1791-1849

• The Daily History of the Debt : Check the public debt on any particular date since 1993.

• Sallie Mae Calculators

• Total Return Calculator (bloomberg.com)
• Universal Currency Converter

Geographic

• How Far is It? : Excellent utility that calculates the "as the crow flies" distance between two locations. 

Maps

• Altapedia
• Cyber Maps
• Etak
• Expedia
• Freetrip
• Geography Network
• Geos
• Great Gallery
• Infoplease
• Lycos
• Mapblast
• Mapquest : One of the best online roadmap and driving directions services available.  The source for many online services that provide maps.
• Maps-on-Us
• Multimap
• National Atlas Canada
• National Geographic
• Odden's
• PCL Map Collection
• Terraserver
• TIGER Map Service : On-line mapping engine from the U.S. Census Bureau -- Topologically Integrated Geographic Encoding and Referencing system. 
• United Nations
• USGS National Atlas
• Xerox PARC
• Yahoo
• Zip2 

Mathematics

• Calculators Online
• Convert It! (Converts anything mathematical to anything else mathematical)
• Distance / Direction Calculator (jewishgen.org) : Calculates the distance and direction between any two points given in latitude and longitude.