Recently when building an admin panel for a client, I decided to add a spotlight sheen effect to the background for a sleeker look. Here's a snap of the completed design:
Here's the CSS(3) that I used to do it. The "sheen" is really just a radial gradient that tapers from a transparent white to full transparency:
background:-webkit-gradient(radial, 250 50,0,250 50,800, from(rgba(255,255,255,.4)),to(transparent)) transparent; background: -moz-radial-gradient(250px 50px, rgba(255,255,255,.4), transparent) transparent;
The effect is applied to a #wrap div, which lies directly on top of the body.