Using Javascript to automatically generate a random number to make sure the banner images don't get cached by browsers...
<script language="JavaScript">
<!-- Hide the script from old browsers --
// CHANGE THESE 3 Variables for yourself
var href = "http://internet/cgi-bin/click.cgi";
var img = "http://internet/cgi-bin/exchange.cgi?account=ACCOUNTNAMEHERE";
// LEAVE THE REST ALONE
var axel = Math.random() + ""
var rand1 = axel.charAt(5)
var rand2 = (axel.charAt(6) == "0") ? "1" : axel.charAt(6)
var random = rand1 + rand2 + ""
var banner = '<TABLE BGCOLOR="black" BORDER=0 CELLSPACING=0 CELLPADDING=0><TR><TD>';
banner += '<a href="' + href + '?x-factor=' + random + '">';
banner += '<img src="' + img + '&x-factor=' + random + '" border=0><a>';
banner += '<TR><TD>';
banner += '<CENTER>';
banner += '<A HREF="/myhomepage"><FONT COLOR="white">Member of MyBanner Exchange...</FONT></A>';
banner += '</CENTER>';
banner += '</TD></TR></TABLE>';
document.write(banner)
//--End Hiding Here -->
</script>