Is there a magnetic stripe card which has the ability to update
itself?  I will be using this card for testing purposes and I would
prefer entering the information directly through the card with a built
on keyboard instead of using the convensional magnetic card writer.

I was hoping to find a device like this (
http://www.radioshack.com/product.asp?catalog_name=CTLG&category_name=CTLG_005_001_001_000&product_id=65-1008
)but with the ability to update the information on the magnetic stripe
on the back.  I am not even sure it is possible, I thought I would
give it a try.