Ant
Apache Ant is a Java-based build tool. In theory, it is kind of like Make, but without Make's wrinkles.

Bee
Bee is a Java-based build tool. Bee inherited some principles of Make. Bee provides more procedure languages constructions, so generally can be used for script programming. It's highly extendable and base DTD can be easily changed, so it allows to create own dialects of Bee.

Centipede
Krysalis Centipede is a project build system based on Apache Ant.

Cruise Control
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.

Invicta
Invicta is an open-source build management tool. Using simple project definition files, it generates powerful build scripts (Apache ANT's), while hiding their complexity.

JMK
A utility for maintaining files in a consistent state. The application is based on the make utility which is part of most Unix systems, but is designed to support the task of writing platform independent makefiles. File names and path lists are written in a canonical form, and translated by jmk into native form. As a result, a makefile can be used to maintain software on a variety of machines and operating systems.

LuntBuild
LuntBuild is a powerful build automation and management tool. Continuous integration or daily build can be easily setup through a clean web interface. Generated builds are well managed through functions such as search, categorization, promotion, patching, deletion, etc. It also acts as a central build artifacts download area for your whole team.

Maven
Maven is a Java project management and project comprehension tool. Maven is based on the concept of a project object model (POM) in that all the artifacts produced by Maven are a result of consulting a well defined model for your project. Builds, documentation, source metrics, and source cross-references are all controlled by your POM. Look here to see the full list of Maven's features.

Rant
Rant stands for 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.

Savant
Savant is an extension to the popular ant build system from the Apache group. In order to use Savant, you need to first download ant version 1.6.1 from Apache's website.