LAM/MPI is an implementation of the Message Passing Interface (MPI) parallel standard that is especially friendly to clusters. It includes a persistent runtime environment for parallel programs, support for all of MPI-1, and a good chunk of MPI-2, such as all of the dynamic functions, one-way communication, C++ bindings, and MPI-IO.
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.
Remote Methode Call is a project to enable calls to methods in remote C++ classes. The transport is implemented as a library, and is free from dealing with the internal RMC stuff, so any C/C++ programmer is able to write a transport for his own purpose. RMC(2) currently has a sockets transport library as reference implementation. It is developed on Linux, and supports Linux on iX86 and PPC. RMC should also work on BeOS. Testers and developers are welcome to the project.
changedfiles is a framework for filesystem replication, security monitoring, and/or automatic file transformations--essentially any application where you'd poll files or directories and either do something to them or send them somewhere else (or both). The difference is that the kernel tells you when they change instead of you having to poll. It's an easy real time FTP push mirror to one or multiple sites. It's also a full fledged MySQL client, so you can do realtime database operations (for example, batch imports). It consists of two parts: a kernel module (works with Linux kernel version 2.4) which reports to a device whenever a file on the filesystem changes, and a daemon which runs in user space and can be configured to do almost any action when a change to a file matching the one of the patterns it looks for is reported. The kernel module is SMP safe and has been tested on Intel, PowerPC, and Alpha.
Pods is a peer-to-peer resource sharing system which allows users to share any resource through the use of an XML-based protocol. The node natively supports disk storage and batch processing, allowing anybody to submit a task to be processed by the entire network. Basic command-line and GTK+ clients are included.