ColorSpace
ColorSpace have set themselves the task to create a place where you can find matching colors, generate nice color palettes and learn more about color conversions and meaning. Sometimes it is hard to find inspiration for a good color scheme or you do not have the time to experiment until you find matching colors.
Their collection of tools has just been released and is currently in beta. At the moment, you can generate color palettes or create nice CSS gradients from colors of your choice.
Related Tools
uiGradients
uiGradients is a community contributed collection of beautiful multi-color gradients, free to use on your next UI or design project.
Grabient
A great tool that generates linear gradients, with the ability to customize each gradient, and download the CSS gradient code.
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.
ColorHunt
Color Hunt is a free and open platform for color inspiration with thousands of trendy hand-picked color palettes.