Apache Qpid is a messaging broker that implements the latest AMQP specification, providing transaction management, queuing, distribution, security, management, clustering, federation, heterogeneous multi-platform support, and much more. It is extremely fast and aims to be 100% AMQP Compliant.
iExploder is like a fire hydrant full of bad HTML and CSS code to test the stability and security of Web browsers. It is available as a standalone Web server or CGI script. It continuously feeds browsers bad data in the hope that they will eventually crash. It is designed to run for hours, or even days until the browser crashes.
The Marionette Collective (mcollective) is a framework to build server orchestration or parallel job execution systems. It uses modern technologies and concepts that make it ideal for large and cloud-based infrastructures. It's specifically geared towards systems administration tasks, but can be seen as a generic framework too.