AsmSpy

A simple command line tool to view assembly references.

How it works:
Simply run AsmSpy giving it a path to your bin directory (the folder where your project's assemblies live).

E.G:
AsmSpy D:\Source\sutekishop\Suteki.Shop\Suteki.Shop\bin

It will output a list of all the assemblies referenced by your assemblies. You can look at the
list to determine where versioining conflicts occur.
 
The output looks something like this:

....
Reference: System.Runtime.Serialization
	3.0.0.0 by Microsoft.ServiceModel.Samples.XmlRpc
	3.0.0.0 by Microsoft.Web.Mvc
	4.0.0.0 by Suteki.Shop
Reference: System.Web.Mvc
	2.0.0.0 by Microsoft.Web.Mvc
	3.0.0.0 by MvcContrib
	3.0.0.0 by MvcContrib.FluentHtml
	3.0.0.0 by Suteki.Common
	2.0.0.0 by Suteki.Common
	3.0.0.0 by Suteki.Shop
	2.0.0.0 by Suteki.Shop
Reference: System.ServiceModel.Web
	3.5.0.0 by Microsoft.Web.Mvc
Reference: System.Web.Abstractions
	3.5.0.0 by Microsoft.Web.Mvc
....

You can see that System.Web.Mvc is referenced by 7 assemblies in my bin folder. Some reference 
version 2.0.0.0 and some version 3.0.0.0. I can now resolve any conflicts.