We address accountability and resource allocation approaches for current and future peer-to-peer systems, including ways of limiting the damage done by freeloaders. We show how micropayments and reputations can help prevent communications denial of service and storage flooding attacks. Our discussion emphasizes accountability solutions that maintain other design requirements, such as anonymity or dynamic networks. After our talk, a conference participant will be in a position to think carefully about how resource allocation problems apply to new peer-to-peer systems and will have some idea of where to start solving these problems.