waterpipe.js is a jQuery plugin for smoky backgrounds generation (HTML5 Canvas).
Background Check is a plugin that automatically switch to a darker or a lighter version of an element depending on the brightness of images behind it.
Adaptive Backgrounds is a simple jQuery plugin to extract the dominant color of an image and apply it to the background of its parent element.
Starscroll is a jQuery plugin that adds a fullscreen starfield, generated in canvas, controlled by css to any div. The parallax responds when user scrolls (no matter how big your content), or when is set to animate.
jQuery.BgSwitcher is a jQuery plugin to switch the background image with effects. Here are effect types that can be used: fade,blind,clip,slide,drop,hide (No effect)
BigVideo.js makes it easy to add fit-to-fill background video to websites. It can play silent ambient background video (or series of videos). Or use it as a player to show video playlist.
BigVideo.js can also show big background images, which is nice to have for showing big background images for devices that don’t have autoplay for ambient video.
Backstretch is a simple jQuery plugin that allows you to add a dynamically-resized background image to any page. It will stretch any image to fit the page, and will automatically resize as the window size changes.