cl-mpi
CL-MPI is a portable, CFFI-based Common Lisp binding for MPI. CL-MPI enables parallel programming in Common Lisp using a message-passing model on either a distributed cluster of machines, or a single multicore machine.

CL-MPI has been successfully tested with SBCL (both 32/64-bit) and CMUCL, with MPICH1.2 and MPICH2 1.0.8.

CL-MPI can also be used to provide "true" multiprocessing for some Common Lisp implementations which don't have native threading capabilities.

Homepage: http://code.google.com/p/cl-mpi/

License: MIT

Tutorials using cl-mpi:

A message-passing "Hello World" in CL-MPI

Parallel Mandelbrot computation in Lisp on a cluster