function banner() {
};

banner = new banner();
number = 0;

// bannerArray
banner[number++] = "<a href='http://www.galaxiworld.com' target='_blank'><img src='http://www.icasinorewards.com/images/banners/gw_468a01.gif' border='0'></a>"
banner[number++] = "<a href='http://www.galaxiworld.com' target='_blank'><img src='http://www.icasinorewards.com/images/banners/gw_468a03.gif' border='0'></a>"
banner[number++] = "<a href='http://www.galaxiworld.com' target='_blank'><img src='http://www.icasinorewards.com/images/banners/gw_eyes_anim.gif' border='0'></a>"
banner[number++] = "<a href='http://www.galaxiworld.com' target='_blank'><img src='http://www.icasinorewards.com/images/banners/gw_banner12.gif' border='0'></a>"
// keep adding items here...

increment = Math.floor(Math.random() * number);

document.write(banner[increment]);