function rndimagem(){

var imagenumber = 3;
var randomnumber = Math.random();
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1;

images = new Array

images[1] = "images/warmup_01.jpg"
images[2] = "images/warmup_02.jpg"
images[3] = "images/warmup_03.jpg"

var image = images[rand1]

document.write('<a href="mailto:info@mediasight.com.br"><img border=0 src="' + image + '"></a>')

//alert(image);

}