In case you are interested in the development of you own Plug-Ins for Internet Explorer 7/8 this framework might come very useful.

SpicIE, which is available as a free download, basically encapsulates COM objects, needed to write an IE Plug-In, and provides you an easy way to write Plug-Ins in a .NET environment, so you can use Visual Studio 2008 and target .NET Framework 2.0, 3.0 or 3.5!

Very useful and efficient!