Rather than pointlessly regurgitate all the usual modelling and simulation links, perhaps I should just direct you to the Population Approach Group in Europe (PAGE) homepage for those.
Here are a few more which are more relevant from a software development point of view:
Perl-speaks-NONMEM (PsN) is a collection of Perl modules and programs aiding in the development of non-linear mixed effect models using NONMEM. The functionality ranges from solutions to simpler tasks such as parameter estimate extraction from output files, data file subsetting and resampling, to advanced computer-intensive statistical methods. PsN includes stand-alone tools for the end-user as well as development libraries for method developers.
Perl is a stable, cross platform programming language. It is used for mission critical projects in the public and private sectors. Perl is Open Source software, licensed under its Artistic License , or the GNU General Public License (GPL).
Xpose is an R library designed to carry out statistical and graphical analysis of NONMEM output.
R is a free software environment for statistical computing and graphics. It compiles and runs on a wide variety of UNIX platforms, Windows and MacOS. One day soon you will need it to get the most out of Census.
From the Embarcadero homepage: "DelphiŪ is the premier development environment for software developers and database application developers who need to rapidly deliver high performance and easy to maintain software applications. Use the powerful Delphi IDE with its visual design surface, extensive component universe and powerful heterogeneous database framework to visually design and deliver applications in a fraction of the time. The powerful Delphi language and compiler deliver high performance and access to all the power and speed of native Windows development. Delphi also provides a comprehensive set of editing, refactoring, and debugging tools in a complete solution focused on making development faster and easier." Census is written in the Delphi dialect of Object Pascal. It, unlike everything else listed here, is not free.
From the JVCL homepage: "The JEDI Visual Component Library (JVCL) consists of a large collection (currently ca 500) visual and non-visual components which can be instantly reused in your Delphi, Kylix and C++ Builder projects. The library is built upon code donated from the JEDI community. It is reformatted to achieve a common look-and-feel, tested, documented and merged into the library. The library is grouped into several categories such as Enhanced Standard, Visual, Non-Visual, Data Aware and many, many more. The library is released to the public under the terms of the Mozilla Public License (MPL) and as such can be freely used in both freeware, shareware, open source and commercial projects." Census makes use of many JCL and JVCL components.
Qt is a comprehensive C++ application development framework. It includes a class library and tools for cross-platform development and internationalization. It incorporates an industry-standard GUI development system, and is the heart of the KDE windowing environment for Linux. Sometime in the far future, Qt will be used to port Census to other platforms.