The current outdated homepage is http://www.bii.a-star.edu.sg/achievements/applications/clustalw/index.php and it contains a link to an older version of the program at http://www.bii.a-star.edu.sg/docs/software/clustalw-mpi-0.13.tar.gz. However, Google tells me the author has moved to and that there is a newer version available at http://kmlvli.com/kuobin/clustalw-mpi/ and http://kmlvli.com/kuobin/clustalw-mpi/clustalw-mpi-0.14.tar.gz
Some extra patches which might be worth to check: http://ftp.debian.org/debian/pool/non-free/c/clustalw-mpi/
What is the current correct website? Debian version is 0.15.
All the links don't work anymore.