Take a dip into how the Connection Points Event Handling mechanism in Classic COM Components can be used by .NET applications to receive event Notifications via the COM Interop.

Aravind, who contributed mightily to the COM interoperability chapter of the Microsoft Press "Inside C#" book, writes this fantastic tutorial on how to use COM components from your .NET C# applications!

Using a Multidimensional SAFEARRAY to pass data across from COM objects

Animating System Tray Icons

Drop down a popdown window instead of a dropdown list from a combobox