Fun With Association Proxies

Not only are tags great, they're a requirement of Web 2.0 (read the handbook). Here's a quick way to pull out those tags in a meaningful way:

class Post < ActiveRecord::Base
  has_many :taggings
  has_many :tags, :through => :taggings do
    def to_s
      self.map(&:name).join(', ')
    end
  end
end

Now, calling @post.tags.to_s will return the list of tag names separated by commas. The real magic is when you do this:

puts "#{@post.tags}"