Is there a tool like this for .NET?

JDepend traverses Java class and source file directories and generates design quality metrics for each Java package. JDepend allows you to automatically measure the quality of a design in terms of its extensibility, reusability, and maintainability to effectively manage and control package dependencies.

A few reasons to use (more on website):

Foster Parallel, Extreme Programming

Packages that are stable should be the centerpieces of a loosely coupled application so the speed of the development team is not adversely affected by the propagation of software changes. Stable packages form design-by-contract facades to other subsystems, allowing teams to develop in parallel at an extreme pace. Moreover, by measuring the software design quality, the overall impact of proposed software changes can be accurately estimated. JDepend allows teams to identify and use desirable dependencies in the system and avoid those dependencies that cause changes to ripple throughout the system.

Isolate Third-Party Package Dependencies