Pre-paid products?

Ok,

I am trying to sale pre-paid phone cards and what I would like is.
Setup an item and when a customer purchases the item. He/she will get an email with the code/key, etc... for their product. The setup process is where I expect to enter the code/key, etc...

I understand Zen cart does down loadable products or virtual. May someone help me with this?

If this is not possible, what module, or software (cms a like) can do this and how do I have Zencart let me create a link to that site?

I know Mamboo/joomla has a lot more modules and hacking potential.

Thanks

This would need to be customized to manage the cards after the order is built to ensure that the right code is sent to the customer with each card purchased ...

This would be best posted in the Commercial Help Wanted to have this designed correctly for this type of product management ...