Ruby Proxies for Scale and Monitoring

EM-Proxy is a barebones proxy implemented with Ruby EventMachine which uses the reactor pattern for handling network connections. The performance overhead in the simplest proxy implementation is roughly 3-5% in the latency – a very low cost for the added functionality. Best of all, it is only ~300 lines of Ruby start to finish, and easily extensible. Take a look through the source, it’s a powerful and wonderful hammer!
(Link: Ruby Proxies for Scale and Monitoring)