This is a Pure CSS The Star Matrix Pre-loaded is a nice css star rating system with detailed description and code.

The author reports that the effect works across a broad range of browsers, as well!

The CSS

.rating{
 width:80px;
 height:16px;
 margin:0 0 20px 0;
 padding:0;
 list-style:none;
 clear:both;
 position:relative;
 background: url(images/star-matrix.gif) no-repeat 0 0;
}
/* add these classes to the ul to effect the change to the correct number of stars */
.nostar {background-position:0 0}
.onestar {background-position:0 -16px}
.twostar {background-position:0 -32px}
.threestar {background-position:0 -48px}
.fourstar {background-position:0 -64px}
.fivestar {background-position:0 -80px}
ul.rating li {
 cursor: pointer;
 /*ie5 mac doesn't like it if the list is floated\*/
 float:left;
 /* end hide*/
 text-indent:-999em;
}
ul.rating li a {
 position:absolute;
 left:0;
 top:0;
 width:16px;
 height:16px;
 text-decoration:none;
 z-index: 200;
}
ul.rating li.one a {left:0}
ul.rating li.two a {left:16px;}
ul.rating li.three a {left:32px;}
ul.rating li.four a {left:48px;}
ul.rating li.five a {left:64px;}
ul.rating li a:hover {
 z-index:2;
 width:80px;
 height:16px;
 overflow:hidden;
 left:0; 
 background: url(images/star-matrix.gif) no-repeat 0 0
}
ul.rating li.one a:hover {background-position:0 -96px;}
ul.rating li.two a:hover {background-position:0 -112px;}
ul.rating li.three a:hover {background-position:0 -128px}
ul.rating li.four a:hover {background-position:0 -144px}
ul.rating li.five a:hover {background-position:0 -160px}
/* end rating code */
h3{margin:0 0 2px 0;font-size:110%}