While Web-based social networking services significantly boost online social interactions in virtual communities, they fail to promote face-to-face interactions in the physical world. Mobile social networks have the potential to enhance social interactions in both virtual and physical world, however, effective ways to unleash this potential still need to be explored. This work attempts to enhance face-to-face social interactions in opportunistic mobile social networks (OMSNs) from a community creation perspective. First, we formulate the community creation problem in OMSNs as a broker based information dissemination and match-making issue. Second, we propose three broker selection metrics (i.e., user popularity, inter-user closeness and user effectiveness) to characterize people's capabilities of acting as brokers. According to these metrics, we further develop different community creation strategies and put forward a unified socially-aware community creation mechanism SOCKER. Based on real human mobility traces, extensive evaluations are conducted showing that SOCKER achieves high community completion ratio and good user experience, while incurring a small overhead