Experiment CSS3 Properties Easily With CSS3 Playground: "
Mike Plate, a freelance web and mobile developer, has created an impressive CSS3 Playground to help seeing the properties in action easily.
The web application enables you to style a box with a text (that can be resized and re-positioned) with the help of sliders and color-pickers.
Once the properties (like radius, box-shadow, CSS3 transforms, etc.) are updated the result is displayed instantly with the CSS code generated.
"