1. Tickets for friends and family.
2. Upgrades, though less so recently since I've been able to upgrade all my recent flights through a combination of VIPOWs (AA term for system-wide upgrades), mileage-based upgrade credits (now worth much less if you trade them in for miles) and complimentary upgrades on full-fare tickets.
3. Last-minute flights when the fare would have been (to me) absurd.