Quovolver

Quovolver is a jQuery plugin for revolving multiple testimonials or quotes in your document. Although, it can also be used to cycle through any group of elements.
http://sebnitu.github.io/Quovolver/

Isotope

Filtering and sorting
http://isotope.metafizzy.co/

Maps

Good for maps and pins
http://gmap3.net/

Waypoints

Execute javascript when you scroll to a point
http://imakewebthings.com/waypoints/

Smooth Scroll

Scrolls to a link on the same page
https://github.com/kswedberg/jquery-smooth-scroll

Fancybox

Opens a window in the same page while fading the background
http://fancyapps.com/fancybox/

bxslider

Slider
http://bxslider.com/

Alpaca

Form made easy
http://www.alpacajs.org/