coolHue is a fancy collection of background gradients ready to be imported in a CSS file as linear-gradient or base64 SVG data.
Freebies tagged: backgrounds
Particleground is a jQuery plugin for snazzy background particle systems. Created and released by jnicol.
uiGradients is a useful tool to get beautiful color gradients for your next design. You can get the CSS code or add your own gradients.
Adaptive Background is a jQuery plugin for extracting dominant colours from images and applying it to its parent. Released by briangonzalez.
Here is a pack including 5 JPG geometric high resolution backgrounds (2500×2500 px) and the original AI file.