var how_many_ads = 4;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1)
{
	id="7";
	url="eelink.net/netservices.html";
	alt="EE-Link Programming & Development";
	img="tech_banner.gif";
	width="468";
	height="60";
	border="0";
}

if (ad==2)
{
	id="8";
	url="naaee.org/";
	alt="North American Association for Environmental Education";
	img="naaee_banner.gif";
	width="468";
	height="60";
	border="0";
}

if (ad==3)
{
	id="9";
	url="eelink.net/usersurvey.html";
	alt="Survey";
	img="surveybanner.gif";
	width="180";
	height="83";
	border="";
}

if (ad==4)
{
	id="7";
	url="eelink.net/netservices.html";
	alt="EE-Link Programming & Development";
	img="tech_banner.gif";
	width="468";
	height="60";
	border="0";
}

	
document.write("<a href=http://www.eelink.net/cgi-bin/banners/banners.pl?id=" + id + "&url=" + url +" target=_blank>");
document.write("<img src=http://www.eelink.net/banners/" + img + " border=" + border + " width=" + width + " height=" + height + " alt='" + alt + "'>");
document.write("</a>");