It's good to be the Mayor.Millions of Starbucks (SBUX) regulars took this butchered Mel Brooks quote to heart when the caffeine distributor began offering its best customers a dollar off a Frappucino. Customer loyalty was based on Foursquare visits and once the location-based social network awarded the Mayor status -- the user who's visited a particular establishment the most -- the discount for the tasty blended beverage is unlocked. And anyone with an iPhone (AAPL) Android (GOOG) BlackBerry (RIMM) or Palm Pre (PALM) and a brief moment to install the Foursquare app is eligible.Granted with 16 600 locations worldwide ...