A trivial CoffeeScript.org -> Javascript plugin for jekyll ( https://github.com/mojombo/jekyll ). Put this file in '_plugins/' and write a YAML header to your .coffee files (i.e. "---\n---\n")

coffeescript_converter.rb

module Jekyll
  require 'coffee-script'
  class CoffeeScriptConverter < Converter
    safe true
    priority :normal

    def matches(ext)
      ext =~ /coffee/i
    end

    def output_ext(ext)
      ".js"
    end

    def convert(content)
      begin
        CoffeeScript.compile content
      rescue StandardError => e
        puts "CoffeeScript error:" + e.message
      end
    end
  end
end

Have you seen/used Jekyll Asset Pipeline?