daterObj = new Date();
minuteCount = daterObj.getMinutes();

if (minuteCount%3 == 0) {
  document.write('<a href="http://www.phand.ca/"><img src="http://www.phand.ca/blipverts/ads/ht-20070812.gif"></a>');
} else if (minuteCount%2 == 0) {
  document.write('<a href="http://www.phonejacks.ca/gdo.html"><img src="http://www.buildinghomes.ca/ads/gdo-20070508.gif"></a>');
} else {
  document.write('<a href="http://www.phonejacks.ca/cv.html"><img src="http://www.phand.ca/blipverts/ads/vac-20071101.gif"></a>');
}