QuickJas is a multi-process (not multi-thread) Java application server. It is well designed for OLTP applications with many large size objects in a JVM of a huge heap. It is a very simple Java application server. It utilizes non-invasive POJO classes as services, and the users are not required to learn any special API to build a client/server system.
SafiServer is an engine that powers the applications called Saflets that control one or more Asterisk PBXs.
(commercial) an enterprise collaboration software system that provides web-based online conference service. It features video conferencing, VoIP audio conferencing, remote PowerPoint presentation, desktop sharing, desktop remote control, local file pushing, instant messaging, and inline browsing
TymeacDSE is a Java Fork-Join application server employing the Divide-and-Conquer methodology in either an embedded or remote (RMI) configuration.
an X Window System server in pure Java under GNU GPL
a very limited SOCKS version 4/5 proxy server, written in Java