I use this in the category page to display "Free Shipping on this Item" When the weight is set to 0
<?php if ($product->product_weight == 0) { ?>
<div class="redtext font10">Free Shipping on This Item </div>
<?php }?>
Here are some for the product page, but you can modify them by changing $this-> to $product->
http://forum.virtuemart.net/index.php?topic=92756.msg305223#msg305223<?php if ($product->product_special == 1){
$image_class='special';}?>
//wrap the image in a div and assign a class to it, and then add the overlay with css
<div class="<?php echo $image_class ?>">
<?php /** @todo make image popup */
echo $product->images[0]->displayMediaThumb('class="browseProductImage" border="0" title="'.$product->product_name.'" ',true,'class="modal"');
?></div>
css
.special{background:URL to image;z-index:1000;THEN ADJUST THE POSITION}
.special browseProductImage{z-index:999}