OK, so I got flamed a bit for sending around this article - .NET Architecture Center: : Secrets of Great Architects. Yes, you have to (try and) ignore the gung-ho Microsoft-speak about "being a *great* architect" but the fundamentals are all there.
Possibly this is a better article Realizing a Service-Oriented Architecture with .NET - it's shorter, easier to read and the pictures make more sense. The scope is a litter narrower, but still a useful read for anyone who thinks 'architecture' is only for buildings.
This info on Developing Identity-Aware ASP.NET Applications is useful and "also provides detailed prescriptive guidance for implementing intranet and extranet ASP.NET applications that are integrated with Active Directory."