distributed.net is a loosely knit group of computer users from all of the world that is taking up challenges requiring lots of computing power (most notably the RC5, DES, and OGR cracking contests). It is simple to participate in the challenges by downloading and running their client software (which uses idle CPU time to complete its tasks).
OOMPI is an object-oriented interface to the MPI message passing library standard. It is used at a much higher level than the standard MPI C++ bindings, providing a full class library that takes advantage of many C++/object oriented abstractions for message passing. It is a thin layer that runs over any MPI-1.1 compliant C implementation.
PVM (Parallel Virtual Machine) is a portable message-passing programming system, designed to link separate host machines to form a ``virtual machine'' which is a single, manageable computing resource. The virtual machine can be composed of hosts of varying types, in physically remote locations. PVM applications can be composed of any number of separate processes, or components, written in a mixture of C, C++ and Fortran. The system is portable to a wide variety of architectures, including workstations, multiprocessors, supercomputers and PCs.
Ganglia is a scalable distributed monitoring system for high-performance computing systems such as clusters and grids. It is based on a hierarchical design targeted at federations of clusters. Ganglia is currently in use on over 500 clusters around the world and has scaled to handle clusters with 2000 nodes.
Key-Cluster is a high availability (HA) system for mission critical applications running on Solaris (Sparc and x86), Linux, and AIX. It guarantees service availability and data access, switching services between machines in case of software or hardware failures in a matter of seconds.