GFortranBinaries - GCC Wiki
- Has links to compiler binaries for Gfortran (GNU Fortran) for Windows, MacOS, and GNU/Linux.
- http://gcc.gnu.org/wiki/GFortranBinaries

GNU Fortran for OS/2, DOS and Win32
- Port of GNU Fortran (g77-0.5.23) for EMX (OS/2 and DOS) and RSX (Win32 console-apps, DOS-DPMI).
- http://programming.ccp14.ac.uk/g77-fortran/~michael/os2/g77/gnu_fortran.html

GOMP
- Project to implement Open MP for the C, C++, and Fortran compilers in GCC.
- http://gcc.gnu.org/projects/gomp/

VFort
- Windows IDE for g77, with pre-compiled SLATEC and DISLIN libraries, by Nikoly and Petr Vabishchevich.
- http://www.imamod.ru/~vab/vfort/

G95
- Ongoing project to create a free, open source Fortran 95 compiler and runtime libraries. Almost all of Fortran 95 is supported. Compiler binaries for Linux, Unix, OS X, and Windows available.
- http://www.g95.org/

GNU Fortran 95
- Ongoing project to develop a Fortran 95 compiler front end, as well as runtime libraries, for the GNU Compiler Collection (GCC).
- http://gcc.gnu.org/fortran/

G77
- Free Fortran 77 compiler using the GCC back-end.
- http://www.gnu.org/software/fortran/fortran.html