Extending IE - links and thoughts

I started writing some extensions to IE, based on MSDN articles, back in 2000 and refined them in 2002. Those primarily used the context menu tips shown in MSDN and the KBase.
The main article is "Browser Extensions" under Web Programming at MSDN.
How to add to the standard context menus of the WebBrowser control

Now I am looking at this again and have found how to add items to the tools menu after seeing some keys in the registry. This is discussed in Adding Menu Items under the above section.
I copied what is done by a 'search related' add-in for MSN does. You need to put a custom GUID under HKLM\SOFTWARE\Microsoft\Internet Explorer\Extensions
I see on this machine than along with the MSN search one, there is also one from Sun for the 'Sun java console'. It has a special dll which it launches.

They both have a CLSID entry which points to shdocvw.dll as inproc server.

Some other links of interest which I have found now are:
Extending the IE Context Menu at The Old New Thing blog - has some other tips