List of integrated development environments

Free/open source IDEs

The GNAT Programming Studio supports development on the following operating systems: GNU/Linux, MS Windows and Solaris Sparc using the following programming languages: Ada, C, C++ and Python
The VIM text editor supports software development on 14 operating system with 39 different compilers. VIM can be extended to support any compiler and programming language.
The GNAVI visual software development environment is an alternative to Delphi and Visual Basic. GNAVI for Microsoft Windows offers comparable features to those languages and is also currently being ported to Mac OS X, Linux and other Unix-like operating systems.
emacs is one of the most popular and flexible IDEs, but its cryptic commands and modes have turned many users off to the GNU application.

Dev-C++, a free open-source IDE for Windows using MinGW
SharpDevelop, a free .NET open-source IDE for Windows (C#/VB.NET and more .NET languages)
Code::Blocks, free Open Source IDE for Windows and Linux. Supports MinGW, VC++ Toolkit, Digital Mars Compiler, and others. Made in C++ with Wxwidgets.

gvim is similar to emacs, in that it provides extensive flexibility to integrate GNU (or any other) utilities, however, it also comes over very cryptic, due to its terse commands and various edit modes.
KDevelop, an emerging IDE from the KDE project based on the GNU development tools (gcc, make, and GDB), which includes a graphical front-end creator. KDevelop is a mature software.
Code::Blocks, free Open Source IDE for C++. Supports workspaces, plugins, custom compilers. GPL licensed.
Anjuta is especially useful for GNOME developers. It is quite stable and in heavy development at the same time.
Gambas, under the GPL licence, is based on a BASIC interpreter with object extensions. It is designed to be a programming language like Visual Basic that can run under Linux.
OpenLDev is a Gtkmm frontend to gcc & g++. It strives to make available a powerful IDE, while remaining simple to use and understand.
kinterdev
Quanta - for web pages

The Eclipse is based on Java can be enhanced with plug-ins, such as DevRocket from MontaVista (for Linux development) which add support for C, C++ (and Java of course).
NetBeans for Java (under a community licence)
Oracle JDeveloper a free Java based IDE that supports development of Java, XML, Web Services, PL/SQL, PHP and more.

With the arrival of Mac OS X, all Linux/Unix tools can run on a Macintosh, provided an X11 Server is also running (one is provided free from Apple). fink is a project which can set up a Macintosh to do this (using free software).

The most popular IDE for Windows is Microsoft's Visual Studio which supports several languages such as C#, C++, and Visual Basic. The previous version of Visual Studio was suffixed with ".NET" to indicate that it supports the new .NET languages: C#, Visual Basic .NET and Managed C++. The latest version is called Visual Studio 2005 and Visual Studio Team System (these products still support .NET languages). Check www.msdn.microsoft.com for latest info.
From Borland, Delphi (based on Pascal) is the successor of Turbo Pascal, which once was a very popular IDE.
From Borland, C++ Builder for the Borland implementation of C++ language
Tornado by Wind River Systems
MinGW Developer Studio, a free but closed-source IDE using MinGW (ported to Linux and FreeBSD as well)
REALbasic is a simple VB like interface, it creates native executable for Windows, Linux and MacOS 9/X.
Stylus Studio XML IDE is a Windows based commercial IDE for developing XML-based software applications.

For the Linux platform, Borland has released Kylix for Object Pascal, C++, and C.
Code Forge
Maguma Workbench

From Borland, JBuilder is one of the most popular commercial offerings for Java IDEs. Borland provides their minimally-equipped version for free. More advanced versions require licenses.
IntelliJ IDEA from JetBrains is a commercial Java development environment. The primary focus of IDEA is programmer productivity, and it includes considerable support for refactoring and test driven design.
The Sun ONE Studio from Sun Microsystems is entirely written in Java. Based on the Open source NetBeans tools platform, Sun ONE Studio software allows one to implement and manage platform-independent Java projects. The Community Edition is free of charge.
The Rational Application Developer and the WebSphere Studio Enterprise Developer from IBM is based on Eclipse and provides extensive support for Java and J2EE artifacts, as well as other languages such as COBOL and PL/I.
JCreator is a Java IDE that functions very similiarly to MSVC++ that is made by Xinox software.

On the Macintosh, the most prevalent IDE in recent times is CodeWarrior from Metrowerks.
Apple also produces a comprehensive IDE for Mac OS X, Xcode, which replaces an earlier, less integrated set of tools called ProjectBuilder.
REALbasic is an easy-to-use cross-platform development environment. It creates native executable for Windows, Linux and MacOS 9/X.