Shopping List Plugin

I need to add a plug in that can create a sort of shopping list for the manager of the site. He would like to be able to select orders that are outstanding and be able to produce an output that will combine those orders and tell what items are required to fill all of the orders. (rather than looking at each individual order) Trying to simplify this so you can understand:

Customer 1 – orders 1 of product A

Customer 2 – orders 2 of product A and 3 of product B

Customer 3 – orders 1 of products B and 6 of product C

I need to produce a list like this:

Product A – 3

Product B – 4

Product C – 6

I don’t know what to call this to search for a plug in, anyone have any suggestions of a plug that will do this or what to search for to find one.

All assistance greatly appreciated!