QuickBuild is a continuous integration and release management server, acting as the central place to produce, test, deploy, and release software builds. It is designed to guard the health of your project by preventing broken builds, and to improve your build delivery process by pushing builds through a customizable pipeline (for example, dev->QA->release) with related information connected such as resolved issues and relevant SCM changes.
mk-configure is a lightweight replacement for GNU autotools written in and for bmake (a portable version of NetBSD make). The main goal is to have only one top-level tool instead of aclocal+automake+autoconf+autoheader. Other goals are clean design, simplicity, and "no code generation".
EBuild is a software project build, dependency management, and reporting technology. The aim is to be able to tackle any build problem in a structured, declarative, and elegant way. It is written in Java, but can be used to build all manner of projects and is extensible via a plugin interface. It is best compared to something like Maven (and in some respects Ivy). It aims to overcome certain design flaws and the resultant unnecessary complexity. The EBuild build model is general, but plugins need to be written in a JVM compatible language. Existing plugins all deal with the Java ecosystem, so EBuild is most suitable for Java and mixed technology software projects.
bmake is a program designed to simplify the maintenance of other programs. Its input is a list of specifications as to the files upon which programs and other files depend. If no -f makefile makefile option is given, bmake will try to open 'makefile' and then 'Makefile' in order to find the specifications.
Fubsy is a tool for efficiently building software. In concrete terms, it lets you conditionally (re)build targets from sources based on which sources have changed since the last build. Typically, targets and sources are all files in a directory tree. In theory, they can be any resource on a computer. More abstractly, Fubsy is an engine for conditional execution of actions based on the dependencies between related resources.
crumb is an experimental build-automation program to provide functionality similar to "make" but with a much better approach, where dependencies for all invocations are automatically detected, by using shared-library level hooks. The spawned processes are also paused if a missing dependency needs to be generated. Oddly, with parallelism, this means that the linker might run before the compiler, but it will get paused until the compiler is done generating the input that it needs. Another purpose of crumb is to provide users with absolutely minimal build description files. This means that the build description files need to be smaller than an equivalent shell script containing the commands that would have built the project directly.