Process Explorer is a really nifty tool, that comes in very handy when you want to take a deep dive into what's running on your machine, and what might be happening behind the scenes:

When you double-click on a .NET application, you get a tab dedicated to AppDomain and performance counter information:

Nice for a quick look around to see what that application is doing.
Mark Russinovich (his
blog is highly recommended) commented on that book during one of his TechEd Europe talks. The book is written (including) by the guy running
rootkit.com, famous for the Hacker Defender rootkit for Windows. Looks like there's yet another book to be added to my backlog for reading this summer <g />.
And it works just fine (here you can get one for yourself):
