found this today at Office Max but could only find it online at Office Depot.

It is a leatherette case for 3×5 cards with a pen loop.

Holds about 25 cards comfortably with outside pockets on both sides for holding a card or two to write on.

Here is the link:

http://www.officedepot.com/a/products/679185/Oxford-At-Hand-Note-Card-Case/

And here is a pic of the thing: