Old school isk doubling game: 1. Send me 20,000,000isk 2. I send back 40,000,000isk 3. You send 80,000,000isk 4. I send 160,000,000isk 5. Continue to double on both sides untill someone stops. It's a game of nerves and I love it, the longer both parties continue to play the larger the reward, but also the larger the risk.