There are sites online where you can give the URL of an image, and it will deconstruct it into a palette.
This is what it did with my banner image:
On Color Hunter it’s similar: put a URL or upload an image, and it gives you the palette and the hexidecimal color numbers for web use.
Behr Paint has a website that helps you find your color combinations.
Color Schemer’s website helps you work from digital color to develop a palette of colors, and gives you some colors to go with your choice as well as letting you lighten or darken your palette.