Clint Cearley has created a free Colour Palette Selector for Photoshop. It is not a complicated tool, but a simple layered PSD file that he created to make colour palettes.
The free Colour Palette Selector has 4 colour wheels that range from light to very dark. Besides the colour wheels there are also 8 masks: Monochromatic, Complementary, Analogous, Split-Complementary, Triadic, Rectangle, Square and Discordant.
The Palette Selector is easy to use, because you only have to rotate the masks over the wheels to choose which colour scheme you want. Clint has included a 2 minute video that will help you get started.