RE: Jason's post and all the others.
A HUGE factor in ICE's usefulness, especially to non-CS type like me, is the fact that most compounds are "published" so that they can be opened and freely edited. You learn a LOT by opening up other people's compounds. And it makes it possible to build on something that's almost-but-not-quite-what-you-need -- which you can't do with a plug-in.