This post is from 2011, about 15 years ago. Some of it may be out of date.
▸ Developer Color Picker
Jake MarshYes. This is so helpful it’s not even funny. This little baby comes to us thanks to Wade Cosgrove.
A custom color picker designed specifically for developers. Makes getting colors out of Photoshop/Acorn mock-ups quick and easy. Currently supports NSColor, UIColor, CGColorRef, CSS and HTML styles.

Supplements the features of the standard color picker in OS X. Simple and perfect. Download it now.
Link: panic.com/~wade/picker