Increase Inventory

Hi All

I am probably just missing something obvious here but I would like to be able to track inventory increases. At the moment all I do is increase the Quantity number in the Product Listing pages. What I would like to be able to do however, is have a record of when and by how much and inventory level has been increased. I guess like placing an order but in reverse. Any ideas? Using version 3.05 but considering 4.