Tcsoftware has developed Syscalculator and is continuing with further development. WinUnit provides flexible unit conversion. It understands 'Number Unit' text input and menu selection. WinUnit is totally data driven from a simple text file definition, allowing new units to be added. It also understands unit classes and systems.
Dimensional analysis is performed to ensure consistent units are used in the conversion.
Help text and a tutorial are supplied. WinUnit really understands unit conversion. You can adjust the value of the entered number by hitting the spin buttons in the bottom right corner. SC Convert converts to and from metric units. That kind of stuff.