how to select all categories select name only , subcategories select name only, limit X items

I have 3 models where 'Categories' have many 'Sub-Categories' and many
'Items' through 'Sub Categories'.
What is a standard Rails 3 way of showing latest few 'items' from each
'sub-categories' that belongs to 'categories'.
So in my view I'd have something like:
category: Music
     sub-category: Classical
            items: mozart, bach (sorted by created_at)
     sub-category:Rock
    ......
Category: Film....

So I would want: all categories select name only , subcategories select
name only, limit X items

Thanks,
Mark