Calendars and clock pickers play a vital role in forms and user interface. Add class and interactivity to your forms with these attractive and intuitive jQuery Calendar Plugins.
The Calendar widget is a JavaScript-based calendar that can either be embedded within a page or popup when a trigger element is clicked. It is based very loosely on the Dynarch Calendar and CalendarView for Prototype.
2. dynDateTime jQuery Plugin-A calendar date and time picker
This jQuery plugin makes it easy to add progressive enhancement to your forms. Add date and time selection to single textfield inputs.
The datePicker plugin is a popup calendar widget and then some. It allows you to add popup calendars to your forms to make it easier for users of your website to enter dates.
4. jQuery ClockPick Plugin -A Time Picker
ClockPick is a timepicker plugin, enabling users to enter a time value into a form field.
Date Input is a no frills date picker plugin for jQuery.
jToday is an easy to use jQuery plugin that displays a “Today Is” like calendar icon. It is suspiciously similar to the event calendar icons on the LinkedIn home page. 
7. jQuery Calendar Widget Plugin
jQuery Calendar Widget Plugin is a simple jQuery Calendar Widget Plugin with a month view.
8. jQuery Plugin jCal – multi-day multi-month calendar datepicker
jQuery Plugin jCal is a super-sleek animated calendar datepicker for multi-day selection with multi-month display.
This is a A plugin providing google-calendar-like functionality to an input where a user can type in a time string.
A highly customisable datepicker. This plugin forms the basis for the jQuery UI Datepicker. It is made available as a separate plugin since the UI team desired simplified functionality for their version.
11. calendarLite jQuery Plugin
The calendarLite jQuery Plugin creates a small flexible calendar that is widgetlike.
12. jMonthCalendar – Full Month Event Calendar jQuery Plugin
jMonthCalendar is a full month calendar that supports events. You simply initialize the calendar with options and an events array and it can handle the rest.
13. jQuery Week Calendar Plugin
jQuery Week Calendar Plugin ia a jquery plugin providing an interactive weekly view of calendar events.
14. FullCalendar – full-sized drag & drop calendar jQuery Plugin
FullCalendar uses AJAX to fetch events on-the-fly for each month and is easily configured to use your own feed format (an extension is provided for Google Calendar).
15. jQuery XML-Calendar Plugin
A small Jquery Calender, which shows a list of events from a xml-file.
16. jQuery Event Calendar Plugin
jQuery Event Calendar Plugin creates a small Jquery Calender, which shows a list of events from a xml-file.
17. JQCalendar jQuery Calendar Plugin
The can be used to create an outlook like calendar, which has DayView,Weekview and ,monthview.
18. jQuery Monthly Ical Plugin
This jQuery Monthly Ical Plugin can be used to create a full month calendar.
I am using jquery.It is the best forever for moving images and some special effects.
The date-time picker http://milesich.com/timepicker/ is excellent too. Just love how the sliders for the time works.
Nice!more:http://www.open-open.com/ajax/DatePicker.htm
thanks these are really usefull, easy and time saving contributions.