INDUCErs: P2P Applications

EarthLink SIPshare, a simple, SIP-based proof-of-concept content sharing application, demonstrates the viability of SIP as a protocol over which peer-to-peer (P2P) applications other than the well-known voice and video cases may be implemented.

Percolation Search in Power Law Networks: Making Unstructured Peer-To-Peer Networks Scalable [pdf] [via]
Some researchers from UCLA have created a search algorithm that uses local rules to find content in ad-hoc networks. They have proved it can find any content in a P2P network of size N in time proportional to O(logN).