Engadget has posted an article on how to easily enter Apple’s 100 million song iTunes contest for free. As we reported last week, Apple is giving away 50 special 20GB iPods — one to the purchaser of each 100,000th song downloaded from the iTunes Music Store between 95 million and 100 million songs. In addition, the person who downloads the 100 millionth song will receive a 17-inch PowerBook, a 40GB iPod, a gift certificate for 10,000 iTunes songs to create the ultimate music library for their iPod and the opportunity to create their own Celebrity Playlist to be published on the iTunes Music Store.