KGamut is a very small but useful tool that enables one to view the color gamut of an image. It is great for analysis and creating color choices for to use in your own projects.
Here is the link to James Gurney's post from where I heard of it and to download KGamut. Just copy and paste the link into your browser.
UPDATED LINK - Here is a new link to the last version of KGamut that was released.