Mozilla Rounded Corners

-moz-border-radius: ul ur lr ll;

-moz-border-radius: 10% 10% 0 0;

-moz-border-radius: 0 0 100% 100%;

-moz-border-radius: 100%;

-moz-border-radius: 15px 0 15px 0;

Here is an example of rounded corners using standard CSS (and silly animated .gifs)