ColorSlurp is a tiny color productivity booster that lives in your menu bar. Now you can pick colors from anywhere on your screen with the magnifier. Or create and edit colors using a variety of color selection tools.
Contrast Safe allows you to check the contrast ratio between 2 colors and validate it against the WCAG standard. A nice companion for every digital designer.
Kelir is a color picker that sits on your menu bar. It includes Palettes and Gradient as well.
Menubar Colors is a Mac menu bar app that allows for quick access to the system-wide color panel.