Using a color picker is a very common tool. After all, who can remember RGB and HEX codes for colors anyways? With sites becoming as application-like as they are, you may be in the situation that you need to add a color selection tool, or color picker to your own site.

I found this PHP class which enables you to do that. And it's not a simple rectangle with the most basic colors, like in AdSense ad setup. This displays a full-blown color spectrum to choose from!