I did used to know the code for that using javascript. I guess I can use all my brainpower to think of it for you. Otherwise you'll have to use PHP, which is for vB.org.
I think I know the code for it in PHP as well
EDIT: Ok, I remembered it almost straight away. here it is (Add this to your body tag, where you want the banner to appear.) Bits in blue require you to change whatever is there.
This will have 3 different images each time the person refreshes DOnt forget to change the width/height ETC.
Code:
<SCRIPT LANGUAGE="JavaScript">
var how_many_ads = 3;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;
if (ad==1) {
txt="TEXT";
url="URL";
alt="ALT TEXT";
banner="BANNER URL";
width="468";
height="60";
}
if (ad==2) {
txt="TEXT";
url="URL";
alt="ALT TEXT";
banner="BANNER URL";
width="468";
height="60";
}
if (ad==3) {
txt="TEXT";
url="URL";
alt="ALT TEXT";
banner="BANNER URL";
width="468";
height="60";
}
document.write('<center>');
document.write('<a href=\"' + url + '\" target=\"_top\">');
document.write('<img src=\"' + banner + '\" width=')
document.write(width + ' height=' + height + ' ');
document.write('alt=\"' + alt + '\" border=0><br>');
document.write('<small>' + txt + '</small></a>');
document.write('</center>');
</SCRIPT>
I think thats it