- stick some sort of forward_day and back_day methods into the base class - make things more OO. - make it impossible to instantiate the base class (ie. make it an ADT). - move the responsibilty for default constructor from subclasses to base class - make Gregorian inherit from Julian rather than the other way around - Add more calendars (ie. Islamic) - Get ahold of my original sources - make the default constructor initialize using today's date. - add a whole lot more test cases to the test suites, particularly boundary conditions - add more argument passing options a la CGI.pm, ie. 'year'=>1974 or -year=>1974 - docs: explain about the second-part approximation that bugged Ed. Sabol - add some form of format specifier to date_string for Gregorian - Conversion between formats that understand time of dat and ones that don't?