Replicating functionality of the hold music "twimlet" from Twilio (http://labs.twilio.com/twimlets/holdmusic)

hold_music.rb

require 'httparty'
require 'twilio'

module Twimlet
  module HoldMusic
    include HTTParty
    AWS_URL = "s3.amazonaws.com"

    def generate_playlist(bukkit='com.twilio.music.classical', options={})
      @bucket = "http://#{bukkit}.#{AWS_URL}"
      @options = options

      get_response
    end

    private
    def get_response
      Twilio::TwiML.build do |res|
        parse_bukkit.each do |obj|
          next unless obj =~ /(\.mp3|\.wav|\.ul)$/
          res.play "#{@bucket}/#{obj}"
          res.say @options[:message] if @options[:message]
        end

        res.redirect(@options[:redirect] || "/")
      end
    end

    def parse_bukkit
      listing = Twimlet::HoldMusic.get @bucket
      listing.parsed_response['ListBucketResult']['Contents'].map {|c| c['Key']}
    end
  end
end

include Twimlet::HoldMusic
generate_playlist

Can be used within Rails by doing
render xml: generate_playlist