Users are sharing vast amounts of social data through social networking platforms accessible by Web and increasingly via mobile devices. This opens an exciting opportunity to extract social perceptions as well as obtain insights relevant to events around us. We discuss the significant need and opportunity for analyzing event-centric user generated content on social networks, present some of the technical challenges and our approach to address them. This includes aggregating social data related to events of interest, along with Web resources (news, Wikipedia pages, multimedia) related to an event of interest, and supporting analysis along spatial, temporal, thematic, and sentiment dimensions. The system is unique in its support for user generated content in developed countries where Twitter is popular, as well as in support for SMS that is popular in emerging regions.