It can display the entire color palette (~16.78 mil. colors) in 6 different color modes.
The picker 4 different sizes; from simple to the most advanced one and has 9 color memories (just like the ones in image editing apps.).
The script is totally skinnable with CSS and it is draggable (can be disabled) for an easier use.
ColorPicker can calculate the web smart/web safe versions of a selected color and much more.