grunt-contrib-jade でいい感じにオプションを渡してあげるやつ

base.config.coffee

module.exports = exports =

  base:
    title: 'タイトルです'
    description: '説明です'
    keywords: "katapad"

    bodyClass: ''
    common:
      img: '../common/img'
      css: '../common/css'
      js:  '../common/js'


    analytics_id: 'UA-xxxxx-xx'


  about:
    title: 'このサイトについて | サイトタイトル'
    bodyClass: 'about'

Gruntfile.coffee

_ = require 'lodash'

module.exports = (grunt) ->

  grunt.loadNpmTasks 'grunt-contrib-jade'

  require('./src/config/jade.config.coffee')(_)
  jadeOptions = require './src/config/base.config.coffee'

  grunt.initConfig
    jade:
      options:
        pretty: true
      about:
        options:
          data: config.getData jadeOptions.base, jadeOptions.about
        files: ['www/misc/about.html': 'src/jade/misc/about.jade']

jade.config.coffee

module.exports = exports = (_) ->
  result =
    config:
      getData: (options...) ->
        if not options
          return null
        for option, i in options
          if i == 0
            r = _.clone option, true
          else
            r = _.merge r, option
        return r


  return result