Add this to your muttrc to enable OSX quicklook of files in the attach menu in mutt. That's right, view shit with the spacebar! Requires, I imagine, ruby 1.9.x as your ruby. Not tested on 1.8.7, but presumed not to work.

quicky.rb

#!/usr/bin/env ruby
#
# Put something god awful in your muttrc like:
# macro attach <space> "<enter-command>unset wait_key<enter><shell-escape>rm -f $HOME/.quicky<enter><save-entry><kill-line>$HOME/.quicky<enter><shell-escape>quicky.rb $HOME/.quicky<enter><enter-command>set wait_key<enter>" "Open with quicklook"
#

require 'tmpdir'

if ARGV.empty?
  puts "need a filename"
  exit 1
end

file = ARGV[0]

if ! File.exists? file
  puts "Canny find #{file}"
  exit 2
end

sowhatisit = %x{ file -I "#{file}" }.chomp

# Now regexp out:
# .quicky: text/html; charset=us-ascii
# Desktop/Screen Shot 2013-03-24 at 21.32.57.png: image/png; charset=binary

regex = /(?<filename>[\w\/\.-]+):\s(?<class>\w+)\/(?<type>\w+);\scharset=(?<charset>[\w\-]+)/
m = sowhatisit.match regex

# lazy?
if m.nil?
  # This probably means the filename has something weird in it.
  require 'rubygems'
  require 'awesome_print'
  ap sowhatisit
  raise
end

Dir.mktmpdir do |dir|
  newfilename = "#{dir}/#{File.basename file}.#{m[:type]}"
  # use the directory...
  FileUtils.cp file, newfilename

  system %{qlmanage -p "#{newfilename}" >/dev/null}
end