Increasingly, city planners and government officials understand that cities are engines of innovation and wealth creation. Equally, there is a growing understanding that the application of technology in support of Smart Cities helps grow the urban economy and deliver better services to citizens. However, often Smart City projects are top- down projects focused on improving city infrastructure using technology. We argue, and our experience over the last decade has shown, that often, citizen driven, or grass-roots based Smart City projects deliver better value and sustainable success. In this paper we report on our work to engage citizens and the technology community in smart city projects and highlight some lessons learnt from our experiences. We show how a modest investment in a Smart City Data Hub (using our IoT platform – WoTKit) plus development tools based on Node-RED helps bootstrap a Smart City innovation cluster.