Dough Lea's Util.concurrent Package
Dawid Kurzyniec's backport of JSR 166
This project contains utility classes that are used by various products and projects inside Atlassian and may have some utility to the world at large.
Concurrent Radix Trees and Concurrent Suffix Trees for Java.
Standardized, efficient versions of utility classes commonly encountered in concurrent Java programming.
JSR 236:Concurrency Utilities for Java EE
JSR-000236 Concurrency Utilities API Classes