uiGradients is a community contributed collection of beautiful multi-color gradients, free to use on your next UI or design project. You also have the ability to download the CSS gradient code.
Color Hunt is a free and open platform for color inspiration with thousands of trendy hand-picked color palettes.
A very useful free color wheel and color palette generator for designers and developers. You can also upload an image to get colors from it.
Gradient by ShopFactory is a great tool for finding wonderful gradients, to use in your next project. It allows you to control the gradients based on different settings.