parallel-ssh

ansible

Ansible is a radically simple IT automation platform that makes your applications and systems easier to deploy and maintain. Automate everything from code deployment to network configuration to cloud management, in a language that approaches plain English, using SSH, with no agents to install on remote systems. https://docs.ansible.com.

rtop

rtop is an interactive, remote system monitoring tool based on SSH

SSH Power Tool

Execute commands and upload files to many servers simultaneously without using pre-shared keys

DSH - Dancer's shell / distributed shell

Wrapper for executing multiple remote shell commands from one command line