arrayOfStuff = ['<img src="/images/footer_image_1_tetra.gif" />', '<img src="/images/footer_image_2_tetra.gif" />', '<img src="/images/footer_image_3_tetra.gif" />', '<img src="/images/footer_image_4_tetra.gif" />'];


document.getElementById("rotate").innerHTML = arrayOfStuff[Math.floor(Math.random()*arrayOfStuff.length)];