Charity Engine - Charity Engine takes enormous, expensive computing jobs and chops them into 1000s of small pieces...
Apache Mesos - Apache Mesos abstracts resources away from machines, enabling fault-tolerant and elastic distributed systems to easily be built and run effectively.
BOINC - BOINC is an open-source software platform for computing using volunteered resources
DIET by Avalon - DIET is a software for grid-computing.
JPPF - The open source grid computing solution.
Quantum Moves - Quantum Moves, part of the scienceathome.