Member Card
The Member Card (Japanese: メンバーズカード Member's Card) is a key item available in Pokémon Diamond, Pearl, and Platinum. It is only obtainable through a Nintendo Event. The Member Card allows players to travel to Newmoon Island, where Darkrai can be obtained.
Nintendo has announced that players of Pokémon Platinum will be able to download the Member Card over the Nintendo Wi-Fi Connection from December 1 to January 15, 2009. Unlike the Secret Key, the Member Card cannot be shared.