Top 10 Message queuing services and Message-oriented middleware

Message-oriented middleware (MOM) is software or hardware infrastructure supporting sending and receiving messages between distributed systems. Message queueing services are message-oriented middleware or MOM deployed in a compute cloud using software as a service model.
Robust messaging for applications. RabbitMQ is a messaging broker - an intermediary for messaging. It gives your applications a common platform to send and receive messages, and your messages a safe place to live until received.
Amazon Simple Queue Service (SQS) is a fast, reliable, scalable & affordable message queuing service. Use SQS to transmit data without losing messages.
Reliable message queue service that lets you connect systems and decouple components. IronMQ supports messages up to 64k; guarantees order; guarantees once only delivery; no delays retrieving messages. Supports REST API and beanstalkd open source protocol. Runs on multiple clouds including AWS and Rackspace.
Apache Kafka is publish-subscribe messaging rethought as a distributed commit log. A single Kafka broker can handle hundreds of megabytes of reads and writes per second from thousands of clients. Kafka is designed to allow a single cluster to serve as the central data backbone for a large organization.
Beanstalk is a simple, fast work queue. Its interface is generic, but was originally designed for reducing the latency of page views in high-volume web applications by running time-consuming tasks asynchronously.
RabbitMQ as a Service. Managed RabbitMQ servers in the cloud. Decouple, distribute and scale your applications with the speed of CloudAMQP
Connect your code in any language, on any platform. Carries messages across inproc, IPC, TCP, TIPC, multicast. Smart patterns like pub-sub, push-pull, and router-dealer. High-speed asynchronous I/O engines, in a tiny library. Backed by a large and active open source community. Supports every modern language and platform. Build any architecture: centralized, distributed, small, or large.
Apache ActiveMQ is the most popular and powerful open source messaging and Integration Patterns server. Apache ActiveMQ is fast, supports many Cross Language Clients and Protocols, comes with easy to use Enterprise Integration Patterns and many advanced features while fully supporting JMS 1.1 and J2EE 1.4. Apache ActiveMQ is released under the Apache 2.0 License
Celery is an asynchronous task queue/job queue based on distributed message passing. It is focused on real-time operation, but supports scheduling as well.
TIBCO Enterprise Message Service is standards-based messaging middleware that simplifies and accelerates the integration and management of data distribution in high-performance, enterprise environments – enabling real-time decision-making and event-driven execution of business operations.