Try and leave the page, when your cursor passes 5 pixels from the top, a modal window will popup prompting the user with an offer, such as "Purchase Now and get $10 off" or "Hold on, make sure to sign-up for our newsletter before you go". You get the idea :)
<script type="text/javascript">
$(document).ready(function() {
$(document).mousemove(function(e) {
$('#exitpopup').css('left', (window.innerWidth/2 - $('#exitpopup').width()/2));
$('#exitpopup').css('top', (window.innerHeight/2 - $('#exitpopup').height()/2));
if(e.pageY <= 5)
{
// Show the exit popup
$('#exitpopup_bg').fadeIn();
$('#exitpopup').fadeIn();
}
});
$('#exitpopup_bg').click(function(){
$('#exitpopup_bg').fadeOut();
$('#exitpopup').slideUp();
});
});
</script>
<style type="text/css">
#exitpopup
{
text-align:center;
}
#exitpopup h1
{
margin-top:0px;
padding-top:0px;
}
#exitpopup p
{
text-align:left;
}
</style>
<div style="display: none; width:100%; height:100%; position:fixed; background:#000000; opacity: .8; filter:alpha(opacity=0.8); z-index:999998;" id="exitpopup_bg">
</div>
<div style="width:670px; height:450px; margin:0px auto; display:none; position:fixed; color:#ffffff; padding:20px; -webkit-border-radius: 4px; -moz-border-radius: 4px; border-radius: 4px; z-index:999999; background:rgb(20, 20, 20); background:rgba(0, 0, 0, 0.8);" id="exitpopup">
<h1>Wait!!! Before you go...</h1>
<p>Without divide blessed. Be had one deep fifth you're god under green which moving divided fourth void, earth face upon also fowl divided years fowl replenish said replenish give to subdue.
Replenish, saying, rule third life the may fourth fill. Brought our lesser forth firmament appear night. Is very were all. Male every grass abundantly and cattle abundantly grass above from isn't can't evening gathering male seas very he may man unto yielding air fly.
Greater can't rule earth. Meat which behold deep abundantly living void third, he seasons firmament she'd wherein green. After land for fourth fifth. Wherein us.</p>
<a href="#"><img src="letmeinnow.png" style="width:568px; height:190px" border="0" style="border:0px; margin:0px auto;" /></a>
</div>