   LAM (Local Area Multicomputer) is an MPI programming environment and
   development system for heterogeneous computers on a network. With LAM,
   a dedicated cluster or an existing network computing infrastructure
   can act as one parallel computer solving one problem.
   
   LAM features extensive debugging support in the application
   development cycle and peak performance for production applications.
   LAM features a full implementation of the [20]MPI communication
   standard (with the exception that canceling sent messages is not
   supported).

http://www.lam-mpi.org/
