I love color. Often times when I'm looking for a color palette to work with I find a website that I like and then view source on it. If I can't grab the colors from the CSS properties, I usually take a screenshot and crop the section I'm interested in, or download the image that represents what colors i'm looking for, and pass it through those free utilities that will tell you the color properties of the image.
During my vacation, I had a goal to get back into signal and image processing, after being out from school for some time now. A simple utility to traverse through the matrix of pixels in an image, and then some RGB math is where I started. In an interest to determine the color palette from an image, I created my own utility that allows me to utilize both my local file system and an external URL. I've opened up my Image Color Swatch utility with the ability for a user to pass a URL in for users to utilize.
If you ever find yourself curious about the colors of an image (like facebook photos), just copy the URL into the swatch utility, and have it analyze the colors for you. Check it out: see an example of the Flickr logo