Although things in the Internet of Things contain considerable amounts of software, developers of such software have no standardized means of maintaining, improving and sharing this software as they can do, e.g., with applications on a smart phone. This limitation can hamper user-driven innovation. In this paper we evaluate the usefulness of the "app store" metaphor as a means of sharing and deploying Internet of Things software among makers. We did a set of interviews and a questionnaire-based survey with a sample of makers in various maker communities. We used this data to extract requirements for an application store, using the common "app store" metaphor as a starting point. The app store concept was developed as a proof of concept implementation, and evaluated through feasibility evaluation and focus group evaluation methods. Our findings show that although the app store metaphor is familiar and easy to grasp, there are some fundamental challenges when adapting the metaphor: (1) The difficulty of supporting the diversity in the software and hardware vendor market, (2) The tension between context awareness and the need for pre-configuration and pre-packaging, and (3) usability challenges related to the number of devices and apps.