proposed product schema

gistfile1.js

var ProductSchema = new Schema({
    categoryId: String
  , department: String
  , ean: String
  , model: String
  , weight: String
  , dimensions: {
      height: String
    , width: String
    , length: String
  }
  , reviews: [{
      author: String
    , title: String
    , rating: String
    , createdAt: Date
    , updatedAt: Date
    , text: String
    , helpfulCount: Number
    , comments: [{
        author: String
      , createdAt: Date
      , updatedAt: Date
      , text: String
    }]
  }]
  , category: String
  , imagesCount: Number
  , images: [{ type: String }]
  , features: []
  , name: String
  , description: String
  , createdAt: { type: Date }
  , updatedAt: { type: Date }
  , price: String
  , upc: String
  , brand: String
  , mpn: String
  , manufacturer: String
  , siteDetails: [{
      sku: String
    , name: String
    , salesRank: String
    , url: String
  }]
})

For the iPod example, those would be separate products (sku). This should hold true for items of different color as well, until we get to clothing. I added in the features object (but left it very wild-west for now).