A friend of mine has developed an assistive browser extension for people with color vision deficiency. It works on the current viewport, a selected area or a DOM element, allowing you to inspect the shades and approximate color names of the pixels. It also outputs color info in RGB and hex, making it useful for web devs, graphic designers as well.

He is also the creator of https://isit.red, a highly performant augmented reality web app that displays color info through a live camera view.