pulpTunes is a Web server for the iTunes, letting you access your music through the Web. Written in Java, it runs on Windows and Mac, and even any other platform like Linux, provided you have an iTunes-like XML library file that points at the path of your music files.
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