What is the most useful plugin in jquery ?

hi,

In Jquery, there are so many plugins are available, mostly DatePicker, time Picker, dialog box,Jquery Tab control, dirtypage plugin etc. are very usefull in radip application devlopment.

some sample pluin links as below.
http://jqueryui.com/demos/datepicker/
http://fgelinas.com/code/timepicker/
http://jonthornton.github.com/jquery-timepicker/
http://coding.smashingmagazine.com/2010/04/27/45-useful-jquery-techniques-and-plugins/
http://jqueryui.com/demos/dialog/

hope this will help you.