The Globus Toolkit provides software tools that make it easier to build computational grids and grid-based applications. http://www.globus.org/toolkit/
CODE is a visual parallel programming system that composes sequential programs into parallel programs for shared-memory multiprocessors and workstations running MPI or PVM. http://www.cs.utexas.edu/users/code/
Suite of tools for managing large clusters of machines including a variety of administration programs such as parallel rcp, parallel rsh, job scheduling, and simple barrier sync. http://www.garbled.net/clusterit.html