Gradientify is a simple jQuery plugin that provides CSS gradient transitions.
Granim.js is a lightweight javascript library to create fluid and interactive gradients animations.
Grade.js is a javascript library that produces complementary gradients generated from the top 2 dominant colours in supplied images.
Shards is a jQuery plugin that builds a CSS multi-layered gradient background on any element - resembling neon shards!
GradientText is an ultra small, easy to use jQuery plugin that will give your standard H1, H2, H3, etc. headers a gradient text color. GradientText automatically converts your text to a HTML5 <canvas> tag with the gradient you specify, and also allows for shadow. The font will stay the same as defined in your CSS.