Smartphones play an important role in mobile social networks. This paper presents a Mobile Message Board (MMB) system for smartphone users to post and share messages in a certain area. Our system is built upon ad-hoc communication model, and allows the users to browse the nearby information without pre-registration with any servers. Our algorithm design focuses on the message management on each phone considering its own schedule of turning the wireless device on and off. We present algorithms for two different cases to maximize the availability of the messages. Furthermore, our evaluation results from experiments and simulation show that the MMB system is efficient and effective for location-based message dissemination.