var banner = new Array();

banner[0]='https://img15.hostingpics.net/pics/943157LineartBann.png';
banner[1]='https://img15.hostingpics.net/pics/499281LineartBann2.png';
banner[2]='https://img15.hostingpics.net/pics/778186LineartBann3.png';

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];