gistfile1.rb

class CommentsController < ApplicationController
  before_filter :find_user, :find_entry, only: :create

  def create
    @comment = @user.comments.new(params[:comment])
    @comment.entry = @entry
    @comment.save

    respond_with @comment
  end
end

class Comment < ActiveRecord::Base
  after_create :post_to_facebook, :if => :share_on_facebook?
  after_create :post_to_twitter, :if => :share_on_twitter?
  after_create :deliver_mailer

  before_save :set_language
  before_create :check_spam

  protected

    def set_language
      # ...
    end

    def post_to_twitter
      # delay this
    end

    def post_to_facebook
      # delay this
    end

    def check_spam
      SpamFilter.new(self.body).spam?
    end

    def deliver_mailer
      CommentMailer.new_comment(self).deliver
    end
end