Jetty is used in a wide variety of projects and products, both in development and production. Jetty can be easily embedded in devices, tools, frameworks, application servers, and clusters. See the Jetty Powered page for more uses of Jetty.
Mina works really fast because it's a deploy Bash script generator. It generates an entire procedure as a Bash script and runs it remotely in the server. Compare this to the likes of Vlad or Capistrano, where each command is run separately on their own SSH sessions. Mina only creates one SSH session per deploy, minimizing the SSH connection overhead.
Apache Tomcat powers numerous large-scale, mission-critical web applications across a diverse range of industries and organizations.
Akka is a toolkit and runtime for building highly concurrent, distributed, and resilient message-driven applications on the JVM.
RxJS is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code. This project is a rewrite of Reactive-Extensions/RxJS with better performance, better modularity, better debuggable call stacks, while staying mostly backwards compatible, with some breaking changes that reduce the API surface.