Goliath (Github) is a non-blocking Ruby web server framework
em-synchrony are Fiber aware EventMachine clients and convenience classes
exceptional_synchrony has extensions to EventMachine/Synchrony to work well with exceptions (via Reactor-Patter Asynchronous Processing in Ruby)
"PostgreSQL" @ Goliath.io Google Group pointing to code examples using postgres-pr & em_postgresql or pg & em-postgresql-adapter
There’s also a very complete demo with asynchronous IO and PostgreSQL here
Building high-performance APIs for the video game industry with Goliath, Grape and EventMachine
angelo is a Sinatra-like DSL for Reel that supports WebSockets and SSE
sinatra-synchrony: Sinatra + EM-Synchrony - fast, concurrent web applications with no callbacks