Oh, how I envy those able to name just three "main" applications! But as Dr Andus did specify just outliner, PIM, writing, note-taking I suppose I would have plump for:

1) OneNote, as a general repository, library and archive

2) ConnectedText, for creating information wikis which will end up as websites

3) The Brain, for a project that is already a website but is too cumbersome to move to ConnectedText

Graham