Product Templates

Hello, I'm having problems showing different templates for different product types. Let's say the shop is selling pdf ebooks and shirts. How can I give to the editors different fields to add the content for each product? I know that the fields in the default product.html are needed anyway but I would like to "extend" this template adding more (different) fields for each product type? Is it possible at all? And if not what would be the recommended way to display different content (except the common defaults) for different product types?