* Java-WebSocket 
http://java-websocket.org/
"A barebones WebSocket client and server implementation written in 100% Java"
* jWebSocket  
http://jwebsocket.org/
"jWebSocket is a pure Java/JavaScript high speed bidirectional communication solution for the Web  server and various clients"
* Grizzly 
http://grizzly.java.net/
Framework for building web servers of various scales and types incl Web Socket client & server apis.
* Apache Tomcat 7
Java Web Container
http://tomcat.apache.org/download-70.cgi
new api & sup[port in 7.0.7: http://tomcat.apache.org/tomcat-7.0-doc/api/index.html?org/apache/catalina/websocket/package-summary.html
* Glassfish
http://glassfish.java.net/
WebSockets via Grizzly and latterly WebSocket SDK also.
* Autobahn  
http://autobahn.ws/developers
Including Android web socket client
* WeberKnecht
http://code.google.com/p/weberknecht/ 
Project with Java SE / Android clients
* Jetty
http://www.eclipse.org/jetty/
Java Web Container including WebSockets support, client and server apis.
JBoss
Java EE App server
https://github.com/mikebrock/jboss-websockets
(in development)
* Caucho Resin
Java Server including web container with WebSockets support. 
see for example: http://www.caucho.com/resin-4.0/examples/websocket-java/index.xtp
* Kaazing WebSocket Gateway
Gateway products, includes Java developer APIs for web sockets.
e.g. http://tech.kaazing.com/documentation/html5/3.3/o_dev_java.html
* WebSocket SDK
Prototyping high level APIs & annotations for Web Sockets.
http://java.net/projects/websocket-sdk
* Webbit http://webbitserver.org/
A Java event based WebSocket and HTTP server
http://groups.google.com/group/webbit  / http://webbitserver.org/
* Servlet 3.1
Proposing API for server side of Http Upgrade mechanism to enable websockets support to be build on the Servlet Container
e.g.: http://java.net/projects/servlet-spec/lists/jsr340-experts/archive/2012-02/message/8
*Atmosphere:
"The only Portable WebSocket/Comet Framework supporting Scala, Groovy and Java"
https://github.com/Atmosphere/atmosphere
*websockets4j:
"Websockets4j Is a simple implementation of the WebSockets protocol. Currently supports the plain text version of Drafts 75 and 76 of the protocol."
http://code.google.com/p/websockets4j/
*GNU WebSocket4J:
"GNU WebSocket4J is a WebSocket protocol implementation in Java. It allows you to build Web applications that interact with applications running in a JVM. GNU WebSocket4J implements both server and client side of the protocol, so it can be used to build both WebSocket servers and clients."
http://maarons.alwaysdata.net/software/GNU/WebSocket4J/
* Netty
Asynchronous event-driven network application framework, including websockets amongst many other things.
 http://netty.io/ / http://netty.io/docs/stable/api/
TorqueBox
Ruby application server built on JBoss AS7 and JRuby.
http://torquebox.org/documentation/
http://torquebox.org/news/2011/08/15/websockets-stomp-and-torquebox/