Frappe Charts : GitHub-inspired simple and modern charts for the web with zero dependencies.
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...
Handsontable : Handsontable is a minimalistic approach to Excel-like table editor in HTML & jQuery. Now with column and row headers!
Morris.js is a lightweight library that uses jQuery and Raphaël to make drawing time-series graphs easy.