Picking up where I have left, I have a nice addition to my collection of colour tools for visualisation experts: http://color.hailpixel.com
What you see below is the whole interface, when you open the website by Devin Hunt.
Choosing colours is easy as pie: Move your mouse pointer around and the area changes its colour. Once you like what you see, click, and the colour will be saved to a part in the browser window, together with its hex code. In the remaining area you can continue to create new colours until you’re satisfied with your palette. Colours can also be selectively deleted again and the URL of the page keeps track of your palette and allows for easy sharing (and, if you will, “export” of the colour values).