Preferences.app is, functionally, a clone of NeXTstep/OPENSTEP tool of the same name. Just like the original program, it's a simple application for setting preferences for the GNUstep system, with a friendly interface. The program is simple, but powerful, in that people can create new modules, called "bundles", that add new things to the program that its original developers did not think of or even intend, that don't require recompiling the main program.
OO Bench compares the speed of the same object-oriented tasks in several object-oriented languages. C++, Objective-C, and Java are currently supported. Support for Smalltalk, CLOS, CSharp, and Eiffel are in development. It aims to be simple, easy to understand, and easy to port. It also aims to follow the idioms and best practices advised by each language as much as possible. It is designed to make it easy to look up how a particular problem is best solved in another language.
Agent Farms is a system for modeling and simulation of complex, multi-agent based systems. The system can be used for creating models of multi-agent systems, interactive and distributed simulation, observation and visualisation of the simulation, and population modification and migration. On those models one can learn about the evolution of strategies in the populations of agents.
distcc is a parallel build system that distributes compilation of C/C++/ObjC code across machines on a network. It can be set up in just a few minutes and makes builds up to ten times faster. It does not require machines to share a filesystem or have the same libraries or header files, and installation does not need superuser privileges.