Here's a little nuance to ReSharper that I really like and use quite a lot. Find a reference under the "References" node of any Visual Studio project. Pick a referenced assembly, right click, and select "Find Dependent Code." This will bring up the familiar "Find Usages" user interface, but with assembly-level dependencies.
Sweet, no?
Aside: Of course if you're looking for an industrial strength solution to analyzing dependencies in your solutions check out Patrick's intense offering in this space, NDepend.