Commercial application for cataloging & categorizing images?
Often the first step in finding a solution is to put a name to it and in this case it sounds very much like you are after a Digital Asset Management package. 

There are many of these available;
 iView Media Pro used to be held as a benchmark and this has had a few transitions of ownership and is now sold as Media Pro 1 by Phase One. Another option could be the Portfolio Suite of products from Extensis. 

You might even find that Apple Aperture or Adobe Lightroom  would fit the bill although these are targeted at photographers shooting in RAW format than being general DAM solutions

There are many more each with their own strengths and you need to review these along with the marketing team to find the best fit for their workflow.