Sometimes you need to render a line item in the cart differently than the rest.  

A sample usage case would be to prevent the quanity of a cart item to be changed.

A built in feature of the cart rendering, is the ability to render each product type with a different template. 
You can define the template via layout xml, using the "addItemRender" action within the 'checkout.cart' block

However, it is impractical to go an create a whole new product type. This article show another, very very easy way

The latest new feature in the Gift Promotion extension, is the ability to generate (and email) coupons on the following customer actions:

Newsletter Subscription
Account Create
Birthdays