Revision3 and Adroll entertain the Valley's ad-slingers

William Hesketh Lever once said, "Half the money I spend on advertising is wasted, and the trouble is I don't know which half." For over a decade, it's been promised that online advertising will fix that. On that note, we made nice with Brooke Hammerling, the bicoastal tech insider who observed that no one can agree…