beanstalkd is a fast, distributed, in-memory workqueue service. Its interface is generic, but was originally designed for reducing the latency of page views in high-volume web applications by running most time-consuming tasks asynchronously.

Philotic, Inc. developed beanstalkd to improve the response time for the Causes on Facebookapplication (with over 9.5 million users). beanstalkd drastically decreased the average response time for the most common pages to a tiny fraction of the original, significantly improving the user experience.

Client libraries for most high level programming languages available.

Needless to say, I love this idea as I love memcached.