P2P applications have found a lot of interest lately but there are open questions about the viability of the revenue models behind P2P applications/ services. In this paper, we discuss revenue models for P2P applications. There is no one size fits all revenue model for the differentP2P applications/ services; hence the quest for viable revenue models requires a differentiated discussion. Our goal is to review some of the fundamental issues which the various P2P application/ service styles face in terms of revenue models. In order is, we suggest an abstract view of P2P interaction to which we map the P2P applications/ services and discuss potential issues which revenue models. We conclude with a short summary and some areas for further research.