Serial numbers: module or core modification ?

[txboy]

I'm studing the way of adding serial numbers to every product unit in stock.

My client asked for a new tab in the admin catalog called "Serial numbers" like the other ones (Features, Attributes...).
I've told him that means a core modification with future update problems, so I propose a module.

What way could be better?

Don't know how difficult could be a core modification like that.
On the other side, I've done modules yet so, perhaps it could be easier to me.

Any comments ?

[olea]

I propose the ProductKeys module on the addons.

With this module, you can indicate which product have to be managed with keys.
Each time an order is validated, module check its content and send the appropriate key to the customer. Keys are also reported on the invoice.

In backOffice, a new tab lists the keys, the product they are associated to an dthe order they are given to.

Keys are :
-- either keys you uploaded through CSV file
-- either a dynamic string constructed on need

You can define if a key can be attributed to a product, to a product attribute or to any attribute of a product.

A demo is available at on my demo site