Free Fortran Compilers
With Salford FTN95: Fortran for Windows you can create console based, conventional Windows and Microsoft .NET applications.
GNU Fortran 95
The GNU Fortran 95 project, or gfortran, is developing a Fortran 95 compiler front end, as well as runtime libraries, for GCC, the GNU Compiler Collection. Gfortran development is a part of the GNU Project, aiming to bring free number crunching to all GNU system variants.
Intel® Fortran Compiler for Linux*
Free evaluation copy can be downloaded for non-commerical uses.
A free multi-platform Fortran77/90/95/2003 compiler. Based on gcc.
Salford FTN95 Personal Edition
FTN95 Personal Edition is now available free of charge to non-commercial users. This version is only licensed for personal usage and is unsupported, programs created with FTN95PE display a banner on execution.
Salford FTN77 Personal Edition Compiler
The Salford FTN77 Personal Edition compiler is a full ANSI Fortran 77 compiler, which also has support for various common extensions. Free for private, non-commercial use.
g77 (GNU Fortran)
g77 is a free Fortran 77 compiler.
This is primarily a C compiler, but if you scroll down you will see a link to a fortran compiler that presumably is an add-in.
Open Watcom is a joint effort between SciTech Software Inc, Sybase, and the Open Source development community to maintain and enhance the Sybase Watcom C/C++ and Fortran compiler products
ADAPTOR is a Fortran Compilation System that supports the analysis, translation and optimization of Fortran 90 programs with parallel and/or optimization directives. It generates new Fortran sources that will be linked with runtime libraries supporting the needed functionality.