<div id="printableArea">
<h1>Print me</h1>
</div>
<input type="button" onclick="printDiv('printableArea')" value="print a div!" />
Javascript:
function printDiv(divName) {
var printContents = document.getElementById(divName).innerHTML;
var originalContents = document.body.innerHTML;
document.body.innerHTML = printContents;
window.print();
document.body.innerHTML = originalContents;
}