Peer-to-peer grids are large-scale, dynamic environments where autonomous sites share computing resources. Producing and maintaining relevant and up-to-date resource information in such environments is a challenging problem, due to the grid scale, the resource heterogeneity, and the variety of user demand. This work proposes a peer-to-peer annotation approach where users can freely annotate available resources as a solution to this problem. We advocate that the proposed approach (i) is scalable, as the job of updating the resource information is divided among users; (ii) will improve resources' utilization, by reducing the amount of resources which are allocated to users without matching their applications constraints; and (iii) will allow resource allocators to increase users' utility, leveraging access to more detailed preference descriptions. The paper also discusses the challenges in implementing and deploying such approach and present solutions to tackle these challenges.