Add on for IE

How to write an Add-on component for Internet Explorer? when you hit the favorites or search menu in IE it opens a small window within IE where we do our stuff. I plan to write an application like that and attach it to IE. ofcourse all the operations will fetch a web site and use IE for displaying it. I can put a webbrowser control in my form, but i want to use IE without any functional limitations.

There are more than 1 way to write an app and i want to find out the best way.

the "favorites" "thing" is a vertical explorer bar.
I haven't written one, yet, but according to the docs you might be able to write one in VB.
Check out MSDN (July 1999)- PlatformSDK - Web Services - Workshop - Reusing Browser Technology - Browser Extensions
requires some registry fiddling and an inprocess Activex dll with Apartment Threading.