WATERFRONT BLUES FESTIVAL July 2-5, Portland, Ore. Top acts: Taj Mahal, Little Feat, John Mayall, Booker T. Tickets: $10 plus two cans of food, per day 2009 donations: 87,577 pounds of food waterfrontbluesfest.com You can’t beat the admission price for the country’s second-largest blues festival. The fundraiser for a local food bank asks for a minimal donation each day in exchange for more than eight hours of music on four stages overlooking...