paletton.com
Paletton is a designer color tool for creating color combinations that work together well. It uses classical color theory with an RYB color wheel to design palettes of one to four hues, each of five shades. Palettes can be previewed in styles including web site design and UI design, and exported in formats such as HTML, CSS, XML, PNG and Photoshop ACO. It is the successor of Color Scheme Designer.