var banner = new Array();

banner[0]='http://imageshack.us/a/img191/8273/99306521.png';
banner[1]='http://imageshack.us/a/img22/3052/65861908.png';
banner[2]='http://imageshack.us/a/img42/7914/46340493.png';
banner[3]='http://imageshack.us/a/img835/9118/36697010.png';
banner[4]='http://imageshack.us/a/img850/484/56932457.png';
banner[5]='http://imageshack.us/a/img33/8929/46976486.png';

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