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.
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.
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.
iHook is a graphical frontend for any command-line executable. It gives scripts a pleasant Aqua face, and allows script writers to provide graphical feedback without having to learn one of the higher APIs available for Mac OS X. iHook accomplishes this through its ability to understand a set of directives. When a script writes an iHook Directive to stdout, iHook will modify its own interface based on the content of the Directive. In this way, a simple shell script can have an Aqua interface, complete with a progress bar and drawer. When launched in the Finder, iHook prompts the user to choose a script to run; iHook also accepts file drops on its icon, and will attempt to run the dropped file. When no user is logged in, iHook tries to execute /etc/logout.hook. This makes iHook highly useful as an interface for Mac OS X LogoutHooks.