Jukebox is a collection of reusable components that allow you to create a flexible server-side and middleware framework. It features semaphores and services (not quite your usual set), a Finite State Machine implementation based on Generics, a Datastream framework (data producers, consumers and loggers), and a JDK 1.6 compliant JMX framework based on Annotations.
CollectionSpy is a Java profiler that focuses on tracking and analyzing your program's usage of Collection Framework containers. It detects hashing container (e.g. HashMap) corruption due to mutating keys. It tracks expensive internal rehashing of containers whose capacity needs expanding. It detects multithreaded access to any unsynchronized container (e.g. HashMap, ArrayList). It visualizes hashing container bucket list lengths, allowing you to diagnose worst-case access performance.