NDepend .Net Dependency Analyzer
NDepend is a very nice .Net Code Metric Analyzer tool that analyzes your application by using some predefined Code-Matrices. it will analyze your Assemblies for dependencies and will provide a clear picture of what is happening inside your application in the form of reports, diagrams and metrics. It is easy to use and with its powerful Code Query Language (CQL) you can build your own queries to inspect your application. it can be integrated with MSBuild or Nant Tasks.
you can download it here