For a second gen nano, the default main menu is this:
- Shuffle Songs
And of course, when you are playing something, "Now Playing" is tacked on at the bottom.
Clicking Music will bring you to:
- Audiobooks (if you have any)
Compilations may also show up if you have that enabled in settings. I think the default is off. Search is present at the very bottom on second gen but not first gen models.
If you have a first gen nano, the above listing should be the same.