Kirk Franklin created the nifty MoreCrayons tool to help web designers more easily visualize the color palette. He recently made fixes so it works with Mozilla as well as other DHTML browsers. I found it a bit surprising that he suggests a 4,096-color Web-Smart palette instead of the traditional 216-color Web-Safe. The color depth available on even 3-year old computer systems is generally better than 256-color, so it probably is past time to be worrying about that limited palette.