How to create associations with Factory Girl?

I watched the RailsCasts episode on factory_girl, and I'm trying to
get out of fixtures.

* Does anybody know an open source project that uses many of the
factory_girls features?

I came up with a pseudo code for possibly showing some association
features I don't understand yet.

Here's the code. It's blog posts with comments plus tagging:
############################ CODE STARTS
create_table "posts", :force => true do |t|
t.string "title"
t.text "content"
end

create_table "comments", :force => true do |t|
t.ingeter "post_id"
t.string "content"
end
create_table "tagging", :force => true do |t|
t.integer "tag_id"
t.integer "post_id"
end

create_table "tags", :force => true do |t|
t.string "name"
end