Dotnet, Sysinternals DebugView, Debug.WriteLine and IIS
I finally managed to write through Debug.WriteLine to Sysinternals DebugView through reading this article. Kudos to the author.
If the original article disappears; here is the recipe in short:
Start Sysinternals Debugview as administrator. Make sure Capture global win32 is checked.
Make sure Visual studio is not attached as debugger because when you run the VS debugger it hogs all information. (In VS you can find the output in the Output window with Show output from Debug.)
Besides Debug.WriteLine also play around with Trace.WriteLine and Console.WriteLine.