User input for listing nodes

On the Overview page where there are columns of each main category with its subcategories below it, it would be nice if below that there was a section (optional via admin's settings/configuration) where each of the above columns was also presented in a dropdown for the user to select what they want to see.

For example, let's say I have two columns of theatrical reviews, a column of cats for type (drama, musical, etc.) and a column for city (New York, Chicago, etc.). And we'll say each category has (nn) nodes.

Type:
Drama (10)
Musical (5)
Comedy (8)
etc.

City:
New York (6)
Chicago (8)
Portland (2)
Los Angeles (9)
etc.

The visitor can click Chicago, for instance, and get every review for Chicago. But perhaps they're interested in only Musicals. If they click Musical instead they will get all musicals but that will include all cities. The visitor is interested in only Chicago.

But if there was a dropdown for each main category (Type and City), the visitor could select Musical and select Chicago. Voila they get the respective nodes specifically. :)

Bob