Mercury is a new logic/functional programming language, which combines the clarity and expressiveness of declarative programming with advanced static analysis and error detection features. Its highly optimized execution algorithm delivers efficiency far in excess of existing logic programming systems, and close to conventional programming systems. Mercury addresses the problems of large-scale program development, allowing modularity, separate compilation, and numerous optimization/time trade-offs.

Mono provides the necessary software to develop and run .NET client and server applications on Linux, Solaris, Mac OS X, Windows, and Unix. Sponsored by Novell (http://www.novell.com), the Mono open source project has an active and enthusiastic contributing community and is positioned to become the leading choice for development of Linux applications.

The DotGNU project aims to be for webservices and for C# programs what GNU/Linux is rapidly becoming for desktop and server applications: the industry leader and provider of Free Software solutions.

SharpDevelop (#develop), the free open-source C# (C Sharp) and VB.NET IDE (Integrated Development Environment.

Dev-Pascal is a full-featured integrated development environment (IDE), which is able to create Windows or console-based Pascal programs using the Free Pascal or GNU Pascal compilers. It can also handle the Insight Debugger.

Free Pascal (aka FPK Pascal) is a 32 and 64 bit professional Pascal compiler. It is available for different processors: Intel x86, Amd64/x86_64, PowerPC, Sparc. The discontinued 1.0 version also supports the Motorola 680x0. The following operating systems are supported: Linux, FreeBSD, Mac OS X/Darwin, Mac OS classic, DOS, Win32, OS/2, Netware (libc and classic) and MorphOS

Inno Pascal is a simple Pascal compiler for Win32. It produces compact, native-code x86 executables without requiring any external assemblers or linkers. It was written entirely from scratch; it is not based on any other existing compilers. Full source code is included under the GPL license.

Lazarus is the class libraries for Free Pascal that emulate Delphi. Free Pascal is a GPL'ed compiler that runs on Linux, Win32, OS/2, 68K and more. Free Pascal is designed to be able to understand and compile Delphi syntax, which is of course OOP. Lazarus is the part of the missing puzzle that will allow you to develop Delphi like programs in all of the above platforms. Unlike Java which strives to be a write once run anywhere, Lazarus and Free Pascal strives for write once compile anywhere. Since the exact same compiler is available on all of the above platforms it means you don't need to do any recoding to produce identical products for different platforms.

The code for the Free Pascal compiler is licensed under the GPL. This means that it is open source, free, whatever name you want to stick to it. You can modify the code if you wish but you MUST distribute those changes or make them available to others if they wish to use it.

Perl is a high-level programming language with an eclectic heritage written by Larry Wall and a cast of thousands. It derives from the ubiquitous C programming language and to a lesser extent from sed, awk, the Unix shell, and at least a dozen other tools and languages. Perl's process, file, and text manipulation facilities make it particularly well-suited for tasks involving quick prototyping, system utilities, software tools, system management tasks, database access, graphical programming, networking, and world wide web programming. These strengths make it especially popular with system administrators and CGI script authors, but mathematicians, geneticists, journalists, and even managers also use Perl. Maybe you should, too.

PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.