Rapid applications development tool and libraries for FPC
The Lazarus IDE is a stable and feature rich visual programming environment for the FreePascal Compiler. It supports the creation of self-standing graphical and console applications and runs on Linux, FreeBSD, MacOSX and Windows.
SPE is a python IDE with auto indentation&completion,call tips,syntax coloring&highlighting,uml viewer,class explorer,source index,todo list,pycrust shell,file browsers,drag&drop,Blender support.Spe ships with wxGlade,PyChecker and Kiki.
rngcc is "really nice GNU C compiler" it's the GUI for the standard GCC on Unix systems rngcc is fully written in c
The GTK+ Development Environment is an light, efficient tool for developing in any language. It acts as a framework around the user's preferred editor and compiler, providing complete project management.