ProCALC 1.1 - Even though the Newton shipped with a built in calculator there was 

early demand for a scientific calculator. proCALC addresses other calculators shortcomings and provides several unique features including - Reassignment of the Newton built in calculator icon (doesn't clutter the extras draw with its own icon). Aesthetic and functional emulation of a "real" calculator.  (yes I know the off switch is a Newton user interface crime  but the HP33 didn't have a close box). Observation of operator precedence (ie 1+2*3 = 7 not 9). Over 50 Scientific and financial functions (inc DEC and HEX conversions) and more!