Collect.js is a convenient and dependency free wrapper for working with arrays and objects.
Yamm is a lightweight and pure CSS megamenu that uses the standard navbar markup and the fluid grid system classes from Bootstrap 3.
Awesome jQuery is a curated list of awesome jQuery plugins, resources and other shiny things.
Flubber is a library to provide a best-guess interpolation for any two arbitrary shapes (or collections of shapes) that results in a reasonably smooth animation.
Chameleon.js is a lightweight jQuery plugin for automatic content colorization.
Warp drive is a lightweight jQuery plugin that helps you create a cool, interactive, configurable, HTML5 canvas based warp drive/starfield effect.
LineProgressbar is a lightweight and customisable jQuery progressbar plugin. It's under MIT licence.
A couple of ideas for typography animations and letter (hover) effects for playful interactions. Anime.js is used to create animations.
Fixit jQuery plugin can be used to fix the element at a certain position when the webpage is scrolled and the element is to be hidden, so that the element stay visible on the webpage.
hiraku.js is a jQuery plugin to create offcanvas menu.
Some little ideas for bouncy and playful tooltip shapes and animations with SVG and anime.js. Among other styles, shape morphing and transform used.
t-scroll is a modern reveal-on-scroll library with useful options and animations.