I spent last Sunday playing around with some of the plugins that people have written for
Lutz Roeder's Reflector. For those who haven't tried it, Reflector is an indispensable disassembler for .NET -- think of ILDASM on steroids. I came across
this link listing available Reflector addins. By far, the most impressive array of addins IMO have been written by Jonathan De Halleux, author of
MbUnit. My favorites are a suite of plugins that he has written for showing assembly, type and method-level dependency graphs. The plugins use QuickGraph to generate SVG graphs. Here's
an example of the dependency graph for CruiseControl.NET (it requires having an
SVG viewer installed to access it).