iTunes filter search results?

I'm not sure how granular you want your filtering, but there's a panel on the left-hand side that allows you to select specific categories for your search results. There's also a Power Search feature which might have more options for you. In this example, I searched for Wolfenstein and can easily filter out Applications by selecting it in the panel that I've highlighted with a red box. This was using iTunes 9.0.2 on OS X.