I tend to copy ideas from other web sites, and I noticed that at play.com
( which is actually in ASP ), they open a popup window from a the ASP when an item on a form is clicked on. The form is nothing special, it handles submitting info for buying products, but interestingly has a zoom for a product image. This is just an additional input for the form.
<input type="hidden" name="returnURL" value="http://www.play.com/DVD/DVD/4-/1064367/Miami-Vice/Product.html" />