function banner() {
};

banner = new banner();
number = 0;

// bannerArray
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/proforma.jpg' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/krve.jpg' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/rtvrijnmond.jpg' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/senr.jpg' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/LogoSchieland.JPG' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/logo_interim_WRD_RGB.jpg' border='0'></a>"
banner[number++] = "<a href='http://www.rondjenoordereiland.nl'><img src='http://www.rondjenoordereiland.nl/images/sponsors/index.1.gif' border='0'></a>"
// keep adding items here...

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

document.write(banner[increment]);