Awfully dumb ruby 4chan downloader. Does the job though.

gistfile1.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'mechanize'

BASE_PAGE_URL = ARGV[0]
LAST_PART_REGEXP = /\/([^\/]+)$/
BASE_DIR = LAST_PART_REGEXP.match(BASE_PAGE_URL)[1]

`mkdir #{BASE_DIR}`

agent = Mechanize.new
page = agent.get BASE_PAGE_URL

page.links.select { |link| (link.dom_class || "").index "fileThumb" }.each do |image_link|
  image_filename = LAST_PART_REGEXP.match(image_link.href)[1]
  puts "Saving #{image_filename}..."
  `wget -nc -P #{BASE_DIR} -nd http:#{image_link.href}`
end