raindrops is a real-time stats toolkit to show statistics for Rack HTTP servers. It is designed for preforking servers such as unicorn, but should support any Rack HTTP server on platforms supporting POSIX shared memory. It may also be used as a generic scoreboard for sharing atomic counters across multiple processes.

em-posixmq integrates posix_mq Ruby library into the EventMachine reactor allowing asynchronous reading from a POSIX message queue

Unicorn controller