Have you ever created a VS Package, tried to run it in Visual Studio only to get the infamous Package Load Failure dialog? Created an editor extension, tried to use it and it never shows up in the VS2010 code editor? Well then the Extension Analyzer is for you.
This tool lets you view logging data from the Visual Studio ActivityLog and MEF tracing, so that you can see errors as they're happening in your component's load. It also lets you run fusion analysis against your assembly to see what kind of managed load failures may be coming from there. It shows what MEF queries Visual Studio makes as different subsystems in the product are being executed. And, even more.
Give it a try and provide any feedback you have on this tool, in it's VS Gallery page.