Music festivals are a great place to talk to consumers, but people are there to have fun, they don't want to feel like a brand has marked them out as a key demographic for a marketing message.
We have seen lots of brilliantly creative guerrilla marketing ideas at festivals over the years that engage revellers in brand messages, rather than bombard them.
Here is a nice example from HP. At the Planeta Terra music festival in Sao Paulo, HP released a giant inflatable ball that was buffeted around by the crowd. Inside the ball was a HD camera that fed pictures, captured on the ball's jouney around the crowd, onto a big screen. Images were also instantly sent to an area at the festival where you could print off the pics or share them online.