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