CSS font-weight thicker than 900?

In CSS 3 there’s another way to make the font size bolder:

color:#888888;    
text-shadow: 2px 0 #888888;
letter-spacing:2px;
font-weight:bold;

EDIT:

For some sort of weird reason this doesn’t look as pretty as it did over an year ago. It only works with text-shadow of 1px (on most common fonts, other thicker fonts might still work with 2px). And with text-shadow of only 1px, there’s no need for such a large letter-spacing.

color:#888888;    
text-shadow: 1px 0 #888888;
letter-spacing:1px;
font-weight:bold;