http://code.msdn.microsoft.com/sourceanalysis
StyleCop is a free static code analysis tool from Microsoft  that checks C# code for conformance to StyleCop's recommended coding styles and a subset of Microsoft's .NET Framework Design Guidelines. StyleCop analyzes the source code, allowing it to enforce a different set of rules from FxCop. The rules are classified into the following categories:

    * Documentation
    * Layout
    * Maintainability
    * Naming
    * Ordering
    * Readability
    * Spacing

StyleCop includes both GUI and command line versions of the tool. It is possible to create new rules to be used.