Free music is awesome, but free music for a cause is better. Neil Young, Foo Fighters, the Black Keys, Band of Horses, and K'naan will tackle Central Park's Great Lawn to raise money and awareness to fight global poverty. To get your hands on tickets, head to the festival's website, and enter the lottery. The only catch? To enter, you need to take action by donating to a worthy cause, learning about the issues, and sharing the festival's petition with friends. A music festival that forces you to be a good person? Hard to argue with that.