The DialogFramework in HotHTML 3 exploits the use of COM to allow third party users to create addons (or dialogs/extensions) for HotHTML 3. Although the SDK ships with only the VB5/6 sample code I was curious how to achieve things with VB.NET. It would still require the .NET Framework (duhh!) but if you can get the SDK ported to VB.NET you can make use of the .NET BCL and write some kick ass stuff...
Well just today on the MSDN Flash newsletter (Frank's back! w00t!) I noticed a KB Article that explains how to effectively allow VB6 to run/call .NET assemblies and .NET assemblies to call VB6 COM objects. See it here.
A similar article was published on CodeProject a while ago, this article seems to put in concrete how to achieve this layer of compatibility. Wonder what the overhead would be?