jQuery has lots of plugins and jQuery UI to improve its functionality in many ways.
Ninja UI is a plugin for the framework that brings new alternatives to them in a single package.
It includes widgets like buttons, accordion, icons, tooltips/modal box, slider, rating, tabs, auto-suggest and canvas-powered loader icon.
Ninja UI
They are unobtrusive and the icons used actually come as a separate plugin that is in the form of web fonts.
P.S. Its documentation is not complete yet but the source of the examples are pretty self-explanatory.