The purpose of the CoCalc project is to develop a simple RPN calculator application for use on laptops running OS X. It has been developed in Cocoa and Objective C, although it may change to a PyObjC application in the future.
Baculator is a Reverse Polish Notation (RPN) calculator program with an infinite scrollable stack and support for most common mathematical operations as well as some more esoteric operations. Available for Unix/Gtk+, Mac OS X, and MS Windows.