http://smml.ru/ есть вот такой сайт. Фон создан вот так:
background-attachment: fixed;
background-image: -webkit-gradient(
linear,
left top,
right bottom,
color-stop(0, #818088),
color-stop(0, #958C8F),
color-stop(1, #393041),
color-stop(1, #514954));
background-image: -o-linear-gradient(right bottom, #818088 0%, #958C8F 0%, #393041 100%, #514954 100%);
background-image: -moz-linear-gradient(right bottom, #818088 0%, #958C8F 0%, #393041 100%, #514954 100%);
background-image: -webkit-linear-gradient(right bottom, #818088 0%, #958C8F 0%, #393041 100%, #514954 100%);
background-image: -ms-linear-gradient(right bottom, #818088 0%, #958C8F 0%, #393041 100%, #514954 100%);
background-image: linear-gradient(to right bottom, #818088 0%, #958C8F 0%, #393041 100%, #514954 100%);
