Richiamo la libreria jquery.
<script src="http://code.jquery.com/jquery-latest.js"></script>
Funzione javascript
<script type="text/javascript">
$(document).ready(function(){
$(document).mousemove(function(e){
var x = e.pageX;
var y = e.pageY;
$("#muovi").css({
"top":y+10,
"left":x+10
})
});
})
</script>
Codice html
<div id="muovi" style="position:absolute;">Appunto sul web</div>