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.
C/C++ system probe, test and automation toolkit
cstem is a portable toolkit for probing and testing C/C++ system. It consist of 4 scripts: cprobe, cltest, cppdef, mkdep. cstem scripts can be used standalone or as part of software build systems. All scripts are portable and have no dependencies. See wiki for more information and examples.
rngcc is "really nice GNU C compiler" it's the GUI for the standard GCC on Unix systems rngcc is fully written in c