Tool for analyzing .Net assemblies
NDepend analyses .NET assemblies of an application and generates design quality metrics. NDepend allows you to automatically measure the quality of a design in terms of its extensibility, reusability and maintainability to effectively manage and control the assemblies’ dependencies of your .NET applications. Moreover, NDepend helps you to get a thorough view of the topology of your application, at component at type and at member level.
Check out the sample report they have on the site. Really cool indeed.
http://smacchia.chez.tiscali.fr/NDepend.html
It's been developed by the same guy who has written this excellent article on iterators in C# 2.0 that not only talks about iterators but also about some cool ways to use iterators in your applications.
http://www.theserverside.net/articles/showarticle.tss?id=IteratorsWithC2