We just added the Image Color Picker. Upload an image and hover to zoom into the pixel under your cursor for a precise color reading.
Click to add that color to a list of HEX/RGB codes, and copy any of them to your clipboard with one click.
For pixel-precise work, click the image to focus it, then use arrow keys to move 1px at a time (Shift+arrow for 10px) and Enter/Space to pick. Use the zoom control to enlarge the image for even finer control.