P3 is middleware used for distributed computing that makes effective use of existing PCs. It enables engineers and scientists to harvest PC's compute power of existing computers in their organization. It also enables outside contributors to participate in research projects that are too massive for a single organization to handle. Unlike Conventional distributed computing projects, in P3 a "participant" means not only a "resource provider" but also a "resource user" because the participant both provides and uses the power.

http://p-three.sf.net/
http://www.jxta.org/universities/aist.html