How do I create rounded corners on web page blocks?

I found a nice tutorial with images and everything for creating really nice looking rounded corners on web pages. I was able to quickly round off my tables with this tool.

One problem that you’ll really want to solve is the color. Using your favorite graphics tool, you can first find the hue and saturation of the color that you want. Then, pull up each of the corner images and change the hue and saturation. This will allow you to match the colors.

You’ll probably have to create several sets of the rounded corners for each of the colors.