Edit in JSFiddle

var img = document.getElementsByTagName("img")[0],
    imagenes = ["http://goo.gl/nSKDVT", "http://goo.gl/3NdA88", "http://goo.gl/cwGrAA"],
    total = imagenes.length,
    cont = 0;

img.src = imagenes[cont];

img.addEventListener("click", function(){
    cont = cont == total - 1 ? 0 : ++cont;
    img.src = imagenes[cont];
}, false);