You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract Twitter Proves Its Worth as a Killer App for Local Businesses New Orleans Pizza Joint, Chicago Yogurt Chain See Results From Promos on Microblogging Service By Abbey Klaassen, Published on May 18, 2009 26 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Register Now Already a member? Log in.