I can get easily see what projects and dlls a single project references from within a Visual Studio .NET project.
Is there any application or use of reflection that
You can create a dependency graph of projects and assemblies in Visual Studio 2010 Ultimate by using Architecture Explorer to browse your solution, select projects and the relationships that you want to visualize, and then create a dependency graph from your selection.
For more info, see the following topics:
How to: Generate Graph Documents from Code: http://msdn.microsoft.com/en-us/library/dd409453%28VS.100%29.aspx#SeeSpecificSource
How to: Find Code Using Architecture Explorer: http://msdn.microsoft.com/en-us/library/dd409431%28VS.100%29.aspx
RC download: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=457bab91-5eb2-4b36-b0f4-d6f34683c62a.
Visual Studio 2010 Architectural Discovery & Modeling Tools forum: http://social.msdn.microsoft.com/Forums/en-US/vsarch/threads