scriptcs - scriptcs makes it easy to write and execute C# with a simple text editor.
Netbeans - NetBeans IDE 7.0. Develop desktop, mobile and web applications with Java, PHP, C/C++ and more. Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
Ecere SDK - A cross-platform Software Development Kit including a GUI toolkit, a 2D/3D graphics engine, a...
Orwell Dev-C - The official site of the Bloodshed Dev-C++ update, which is fully portable, and optionally ships with a 64bit compiler.
Eclipse - Eclipse is an open source community, whose projects are focused on building an open development platform comprised of extensible frameworks, tools and runtimes for building, deploying and managing software across the lifecycle.
Qt Creator - Qt Creator is a cross-platform C++, JavaScript and QML integrated development environment. It is the fastest, easiest and most fun experience a C++ developer could wish for.