Apache Ant is a Java-based build tool. It is kind of like Make utility, but without Make's wrinkles. A must for java build system.

CruiseControl is a framework for a continuous build process. It includes, but is not limited to, plugins for email notification, Ant, and various source control tools. A web interface is provided to view the details of the current and previous builds.

Rant is known as Remote Ant. It is a distributed build system that allows an Ant build file to launch builds on other systems and receive exceptions should they occur.