junixsocket is a Java/JNI library that allows the use of Unix Domain Sockets (AF_UNIX sockets) from Java. In contrast to other implementations, junixsocket extends the Java Sockets API (java.net.Socket, java.net.SocketAddress, etc.) and even supports RMI over AF_UNIX. It is also possible to use it in conjunction with Connector/J to connect to a local MySQL server via Unix domain sockets.
Zynaptic Reaction is a flexible asynchronous programming framework for Java which may be used to implement complex event-driven applications. It is heavily influenced by the Twisted programming framework developed by TwistedMatrix Labs for the Python programming language. The focus of the Reaction library is on the concurrency and callback model and as such it is application neutral. It can be used to manage lots of concurrent I/O or to farm out compute intensive tasks to multicore processors. As well as being usable as a basic Java library, Reaction can also run as an independent OSGi service and integrate into any GUI framework you choose.