Checkout and Customer Checkout Comment

Has anyone thought about this, or solved this?

The scenario is... the ability to order greeting cards, and be able to add one or two lines that will be printed onto the greeting cards. Is there anything in the werks to allow a customer to be able to send text along with an order, that is associated with a specific product? Most products would not have or need this capability... it only needs to be associated with a select few.