iTunes Plugin Programming?

[cheesewhiz]

So this is a weird one. I've been playing with the iTunes COM interface on windows (with some simple javascript), and I'm ready to take it to the next level. I want to create another option in the itunes list on the left (Where you can see "Library", "Podcasts", "Music Store", etc., but I have no idea how to add anything to that list. I also want to display stuff in the right pane -- probably just a web page w/parameters. I know that you can use visualizer plugins to display this, but that seems sort of hackish and it's out of the way. I want it right there. If anyone has done this (I'd like JScript or C#, but I will take anything), can you help me out?