I think I'll add the Show Desktop button by default since it's rather useful (of course, it does the same as Ctrl+Alt+D). I don't think the Trash icon is useful for most people by default. Adding a Help button isn't very useful since Help would either describe Unity or GNOME Shell which are dramatically different than GNOME panel. A single Firefox button wouldn't be useful to Chrome/Chromium users and there's almost as many of those as there are Firefox users.
I think I'll add the Show Desktop button by default since it's rather useful (of course, it does the same as Ctrl+Alt+D). I don't think the Trash icon is useful for most people by default. Adding a Help button isn't very useful since Help would either describe Unity or GNOME Shell which are dramatically different than GNOME panel. A single Firefox button wouldn't be useful to Chrome/Chromium users and there's almost as many of those as there are Firefox users.