Together they are unbeatable! It’s such a joy to use them for rounded corners with a drop shadow. The box above uses: border-radius: 8px;
box-shadow: 0px 1px 3px rgba(0,0,0,0.2); to do the magic.

And it get’s better: They even work on embeded Flash! See the 4px rounded corners live in the photo/video section.

Note: This is CSS3 and not all browsers support it yet, like our friend IE.