class Image < ActiveRecord::Base
  attr_accessible :description, :name, :size, :image, :tag_ids

  has_many :taggings, :dependent => :destroy
  has_many :tags, :through => :taggings
end

class Tag < ActiveRecord::Base
  attr_accessible :name
  has_many :taggings, :dependent => :destroy
  has_many :images, :through => :taggings

end

resources :images do
    get 'confirm_destroy', :on => :member
end
resources :tags

- @tags.each do |tag|
  = link_to(tag.name, tag)

class Tag < ActiveRecord::Base
  attr_accessible :name
  has_many :taggings, :dependent => :destroy
  has_many :images, :through => :taggings

    def to_param
        name
    end
end

class TagsController < ApplicationController

    def show
        @tag = Tag.find_by_name(params[:id])
    end

    ...

end