What's your favorite Prototype framework compatible, javascript date picker?

Please one library per answer so that people can vote for the individually.

From stackoverflow Jay Stramel

• Calendar Date Select

  From CMS

• Yahoo! UI Library: Calendar

  "The Calendar component is a UI control that enables users to choose one or more dates from a graphical calendar presented in a single month or multi month interface. Calendars are generated entirely via script and can be navigated without any page refreshes."

  "You'll find the Calendar Control to be a useful and easy-to-implement enhancement to any date-selection interaction; you may also find that the Calendar's foundation classes are a good place to start for more complex interfaces that visually organize date-tagged information (like appointments, photos, events, etc.)."

  From Paul Dixon

• jQuery's UI.DatePicker

  (Prototype compatible via JQuery.noConflict())

  micahwittman : Along with date, add formatted time: http://derekallard.com/blog/post/adding-time-to-jquery-ui-datepicker/
  From micahwittman

• Timeframe for visual selection of date ranges...

  micahwittman : @CMS Wow - Timeframe is really nice. I'd upvote twice if I could. I would say it rivals or bests the date range ui on google analytics.

  CMS : Thanks micahwittman, it's a really really nice control :) ...
  From CMS

• Date.js is pretty cool, although it's technically not a date picker per se.

  From Paul Wicks

• Scal is a simple, javascript calendar/date picker based on the Prototype JS library.

  To create a calendar, just create an instance of scal with your base element and the update callback, along with optional parameters:

  var cal = new scal('samplecal', updateelement, {
    oncalchange: function(d) {
      alert('Calendar Change: ' + d.format('yyyy-mm-dd'));
    }
  });
  

  Check out the demo and its cookbook.

  From aemkei

• ExtJS works well with Prototype and has a widgets that constantly gets extended by its community. DatePicker is one of them.

  demo: http://www.lubber.de/extjs/datepickerplus/

  From JasonOng