It would be really cool to see CMYK support - I prefer HSL to RGB to find good colours that work together; but I prefer CMYK to even HSL

It would also be cool if multiple copies of the tool could dynamically be added to pick multiple colours at a time - with, say, up to eight blocks at the top showing the current colour for each selector, and a text box to easily copy the various colours...

Thanks for sharing - this is nice!