The blockchain concept and technology are impacting many different research and application fields; hence, many are looking at the blockchain as a chance to solve long-standing problems or gain novel benefits. In the agent community several authors are proposing their own combination of agent-oriented technology and blockchain to address both old and new challenges. In this paper we aim at clarifying which are the opportunities, the dimensions to consider, and the alternative approaches available for integrating agents and blockchain, by proposing a roadmap and illustrating the issues yet to be addressed. Then, as both validation of our roadmap and grounds for future development, we discuss the case of Tenderfone, a custom blockchain integrating concepts borrowed from agent-oriented programming.