Sometimes an advertising campaign takes on a life of its own. T-Mobile’s outlandish flash mob events aren’t just visually spectacular- they also manage to resonate emotionally. Their latest effort finds thousands of people singing along to “Hey Jude” in London’s Trafalgar Square. It’s quite a sight. Not every advertiser has the resources to equal T-Mobile’s “Life’s For Sharing” campaign. But imagination, creativity and inspiration are free.