jmxsh is a fully scriptable command-line JMX client based on Tcl. It is simply a Tcl interpreter powered by Java/Tcl (with command-line history and editing provided by JLine) that has special command-line options for connecting to JMX servers and special Tcl commands for interacting with JMX servers. jmxsh is capable of simultaneously connecting to multiple JMX servers. There's also a "browse mode" for exploring the remote JMX namespace without knowing beforehand the names of MBeans or their properties. jmxsh and all its dependencies are distributed in a self-contained executable jar file for ease of use.
jmxtrans is effectively the missing connector between JMX and whatever logging or graphing package that you can dream up. jmxtrans is very powerful tool that reads JSON configuration files specifying servers/ports and JMX domains/attributes and then outputs the data in whatever format you want via special "Writer" objects that you can code up yourself. It does this with a very efficient engine design that will scale to querying literally thousands of machines. The core engine is pretty solid and writers are included for cacti/rrdtool, graphite, and stdout.
jniThreadCPUUsage is a Java library to get the amount of user and system CPU time used per thread. This is done via JNI, which calls getrusage() on the system. getrusage() is only available on Linux 2.6.26 or later and Solaris. One useful application of this is measuring the amount of CPU time used for a servlet request. getrusage() CPU time reporting is better than using the real time clock because it measures actual CPU time used and disregards times when the thread is idle or waiting (such as when it is waiting for network I/O).
jrawio is a Service Provider Implementation for the Java Image I/O API that provides the capability to read images stored in a "camera raw" format. It supports various formats from the major camera manufacturers (e.g. NEF, CRW, CR2, PEF, SRF, MRW) as well as Adobe Digital Negative Format (DNG). It is made of pure Java code and does not require any native library.
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.
kongcurrent provides an easy-to use helper to assist debugging issues which cause exceptions under concurrent access. It was inspired by a problem in which a non-thread-safe Map object held by a third party framework was accidentally shared between threads, causing a ConcurrentModificationException. The helper (a "monitor") creates a proxied version of an object implementing some interface. The proxy can track invocations of the objects' methods and can report on potential concurrent access on the object. This can be used to help find code paths which concurrently access the object through its interface methods. By design, the helper is extensible, and can be adapted to more specific needs.