uiGradients
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.
Related Tools
Adobe Color
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.
Dribbble Color
Dribbble Color is a wonderful tool that allows you to display all dribbble shots, based on certain colors.
Coolors
The super fast color schemes generator! The Coolors app allows you to create, save and share perfect color palettes in seconds!
Grabient
A great tool that generates linear gradients, with the ability to customize each gradient, and download the CSS gradient code.