function background() {
};

background = new background();
number = 0;

background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/home_tracy.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/home_bridge.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/boston_night_panorama.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/cranberry.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/shamoo.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/home_lube.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/boston_night_panorama.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/bike.jpg) top right no-repeat;}</style>"
background[number++] = "<style type='text/css'>#random_img{background: url(images/home_array/home_baby.jpg) top right no-repeat;}</style>"

increment = Math.floor(Math.random() * number);
document.write(background[increment]);