var trailimage=["../images/trail.gif", 30, 30] //image path, plus width and height
document.write('<div id="trailImage" style="position:absolute; visibility:visible; left:0px; top:0px; width:1px; height:1px;"><img src="'+trailimage[0]+'" border="0" width="'+trailimage[1]+'px" height="'+trailimage[2]+'px"></div>')

var divName = 'trailImage';
var offX = 15;
var offY = -20;

function mouseX(evt) {if (!evt) evt = window.event; if (evt.pageX) return evt.pageX; else if (evt.clientX)return evt.clientX + (document.documentElement.scrollLeft ?  document.documentElement.scrollLeft : document.body.scrollLeft); else return 0;}
function mouseY(evt) {if (!evt) evt = window.event; if (evt.pageY) return evt.pageY; else if (evt.clientY)return evt.clientY + (document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop); else return 0;}

function follow(evt) {if (document.getElementById) {var obj = document.getElementById(divName).style; obj.visibility = 'visible';
obj.left = (parseInt(mouseX(evt))+offX) + 'px';
obj.top = (parseInt(mouseY(evt))+offY) + 'px';}}
document.onmousemove = follow;