Diurna is a command-line program intended as a complement to the common Date program found on GNULinux systems. Diurna converts the system date from the modern, to the ancient Roman form complete with latin and roman numerals.
A Roman Numeral Calculator. Ratio Mercatoris (formerly Ratiocinator) is a calculator program using Roman Numerals. Also, has built-in Financial and Scientific (Ancient Rome) functions.