Just a quick idea I had while playing with an image. It would be useful to have some basic colour rules built into the picker, so you can quickly grab a compemetary/contrasting/analagous/triad colour scheme – like Adobe Kuler. Not suggesting anything as complex as that, but just a quick way of having colour suggestions, while noodling around. And not everyone knows their colour theory!
Most of those color pickers are pre-packaged systems that can be chosen, sort of like a plugin sort of thing. Doesn't seem to be too tough of a thing to do. There are dozens of color pickers out there, would be cool to be able to pick one.
Disclaimer- Making requests like this is very easy. implementing them most likely more complicated than we can imagine. Coders make magic happen.