In one of my past jobs, I've implemented a full blown exstensible VB6 application, which used the COM Scripting engine provided by Microsoft. One of the best things about it was that it allowed me to expose the full object model of my application to outside scripts. I could even expose events of my objects and have them call scripting procedures on the outside. It was pure bliss to see it in action, and was a great help when it came time to add minor (and major) tweaks at the client's side.
Exposing your object including its events to scripting in VB6 was a matter of 3 lines of code. Very easy. I don't see it being that easy with .Net. Not today, anyhow. Alintex came up with their scripting .Net support. so this is something that I'll have to check out, but what's realy missing is great *free* support for this kind of easy scripting. It should not be as complicated as depicted in the article above.