Handsontable : Handsontable is a minimalistic approach to Excel-like table editor in HTML & jQuery. Now with column and row headers!
hoverIntent jQuery Plug-in : hoverIntent is a plug-in that attempts to determine the user's intent... like a crystal ball, only with mouse movement! It is similar to jQuery's hove...
Sammy.js : Sammy is a tiny javascript framework built on top of jQuery, It's RESTful Evented Javascript.
jquip : Smaller, Lighter, Faster, more modular jQuery - include only the parts you want! Don't use it, Don't include it.
Morris.js : Morris.js is a lightweight library that uses jQuery and Raphaël to make drawing time-series graphs easy.