Initial work on peer-to-peer systems has focused on finding information in large-scale decentralized systems. More recently, the focus has shifted to sharing information in such contexts. Meeting this goal in environments in which many data replicas change their state frequently is very challenging. The objectives of the work described in this paper is two-fold: designing mechanisms that allow information lookup based not only on unique data keys, but also on meta data, and enabling efficient and scalable implementation of data sharing by providing a notion of consistency weaker than existent proposals. The paper formalizes the notion of weak consistency in peer-to-peer environments, and presents detailed implementations of our information lookup and data sharing mechanisms.