I came across an interesting tool the other day that can be used to debug and diagnose configuration problems with Kerberos. DelegConfig is an ASP.NET application that you install to generate a troubleshooting report about your IIS configuration, Kerberos credential usage, and delegation settings. You configure the DelegConfig installation with the service account you intend to use for your application and visit the report page with the end user account you intend to use. The report also includes a wizard for setting up a simulation of a multi-tier service.