This add on will allow you to view stock levels for your products as a report in your admin.  Fields that are shown on the report include:

Product ID
Quantity in Stock
Product title
Master category
Product Price
Extended Retail value of stock on hand

You can sort by all of the above fields as well as filtering by category as opposed to showing all products.  

Zen Cart Version:  1.3.9, 1.5.0, 1.5.1, 1.5.3