From humble beginnings as a sales associate in 1985 with no college education Brian Dunn climbed the corporate ladder at Best Buy, eventually finding himself at the top of the food chain in 2009 when he took over as CEO. Unfortunately, for this rags-to-riches poster-boy, his reign has come to an end. Dunn and BBY announced today that the long-time employee will be stepping down from his position as chief executive and will be replaced in the interim by board member Mike Mikan. The big box retailer said in a statement that the agreement was mutual an