Convert Center is a measurement conversion tool that provides you with over 100,000 possible conversions from over 1,000 different measurement units, and allows you to add your own custom units as well.
License: Freeware
OS Support: WinXP, WinNT 4.x, WinNT 3.x, WinME, Win2003, Win2000, Win Vista, Win98, Win95

Unit Conversion Software for Windows to easily convert between 758 units of measurement Includes Units for Temperature, Distance, Mass, Area, Volume, Pressure, Velocity, Acceleration, Force, Energy, Power, Fuel Consumption, Flow and more.
License: Shareware
OS Support: WinXP, Win2000, Win Vista

ESBPCS-Calcs is a subset of ESBPCS containing Components and Routines for Calculators and Unit Conversion for Delphi & C++ Builder Includes Data Aware Components and full source, as well as a good subset of the ESBPCScontrols.
License: Shareware
OS Support: WinXP, Win2000, Win Vista