HotQueue is a Python library that allows you to use Redis as a message queue within your Python programs.

Octobot is a task queue worker for applications that must process message queues with extremely high throughput, minimal latency, and high availability - especially those sensitive to the overhead implicit in receiving and processing many lightweight tasks, such as message delivery systems.

Celery is a task queue/job queue based on distributed message passing. It is focused on real-time operation, but support scheduling as well.

MessagePack is a binary-based efficient object serialization library. It enables to exchange structured objects between many languages like JSON. But unlike JSON, it is very fast and small.

celery is a distributed task queue framework for Django. It is used for executing tasks asynchronously, routed to one or more worker servers, running concurrently using multiprocessing.

High speed message queuing library.

Distributed in-memory application cache platform. Like memcached for Windows.

Scalr is a fully redundant, self-curing and self-scaling hosting environment utilizing Amazon's EC2.

AMQP enables complete interoperability for messaging middleware, both the networking protocol and the semantics of broker services are defined in AMQP.

MogileFS is an open source distributed file system.