A few weeks ago I spoke at the Seattle .NET Developers Association user group. I did a demo-centric presentation (no slides) showing how to create a .NET wrapper class in Visual Studio 2005, expose them as COM objects with proper interface declarations, and then use it in Visual Basic 6.0 as well as in VBA-based Microsoft Office applications. Included in the demos will be a new utility preview download called NET4COM (included in the the Sedna CTP1 download), which are wrapper classes of many useful functions in Microsoft .NET Framework 2.0 classes, including features in the Visual Basic 2005 My object, and code snippets included in Visual Studio 2005. Many of these .NET wrapper classes for COM clients compliment ideas described in the existing documents found on the Coexisting with Visual Basic 6.0 web page.
The NET4COM utility idea is to bundle up many functions that the .NET Framework offers and expose them as COM objects for use with VFP or other COM clients. Some of these features can be done with Windows API calls or other COM objects that exist, but in the future more and more functionality will be evolving on the .NET platform rather than the COM based Win32 platform. An example would be to use the NET4COM.RegEx class instead of using the CREATEOBJECT("VBScript.RegExp") COM object. 
Cindy Winegarden blogged about some additional information about NET4COM. The NET4COM existing and upcoming classes offer a toolkit to grow in that area as well as just being a good working sample of how to build your own .NET wrappers for COM.