A lot of jQuery plug-ins have become obsolete due to HTML5 and CSS3, those are mostly look enhancing plug-ins and text placeholder, which is now standard in HTML.
I have chosen the more common optimization scripts and almost all are simple ones making it easier to implement in your design or to customize. Forms are a very integral part of online interaction, it is the interface from which all data is submitted. An usable and easy to use form is guaranteed to be used again by your users.
Turn any webform into a powerful wizard with jQuery
Give Your Characters a NobleCount
Submit A Form Without Page Refresh
Simple Chained Combobox
Ajax Upload; A file upload script with progress-bar, drag-and-drop
Date Range Picker using jQuery UI 1.7 and jQuery UI CSS Framework
jQuery Add/Remove Input Fields