In one of the Linux Magazine articles, I came across this shell called dsh (Distributed Shell). The name is a misnomer as it is actually not a shell. It is a wrapper to invoke shell commands using ssh (or any other configured shell) in different machines. Nevertheless, I think this tool would be of tremendous help when the same command is to be run in multiple machines, which is what most of the admins do often. An example given in the Linux Magazine article is to run last command in multiple machines to see the login/logout activity.