KronoClass is a PHP class which performs various operations on dates and times. It is based on internal arrays instead of the LC_TIME setting of PHP. Its language support includes Italian, English, French, German, Spanish, Portuguese, Japanese, Norwegian, Indonesian, Finnish, and Dutch.
Date_Calc is a calendar class used to calculate and manipulate calendar dates and retrieve dates in a calendar format. It does not rely on 32-bit system date stamps, so you can display calendars and compare dates that date pre 1970 and post 2038.
Calendario Class is a PHP class that helps you to create calendar and organizers. It's highly configurable, letting you choose how many days are in a week, when a week starts, the details of the HTML output, and so on. It also knows about holidays.