I stumbled across a useful tool on the Wet Canvas forum a few days ago and forgot to mention it. It's called "Virtual Palette". You can mix specific paints virtually and this tool will show you the resulting colors. It's worth checking out: http://www.wetcanvas.com/colormixer/ You have to register to use it, but it's also worth registering as the forum is wonderful. Even if you're just a lurker like yours truly.