img { box-shadow: 2px 2px 5px #11111; -moz-box-shadow: 2px 2px 5px #11111; -webkit-box-shadow: 2px 2px 5px #11111; }

This will add a subtle drop shadow to all images on a page.  Works with all major browsers excluding Internet Explorer 8 and below.  The beta version of Internet Explorer does support box-shadow.  There's a nice writeup on box shadow here: http://www.css3.info/preview/box-shadow/

css3 image drop shadow

css, CSS3

CSS