Gfortran is the name of the GNU Fortran project, developing a free Fortran 95/2003/2008 compiler for GCC, the GNU Compiler Collection. The gfortran development effort uses an open development environment in order to attract a larger team of developers and to ensure that gfortran can work on multiple architectures and diverse environments.
This wiki contains links to binary packages for gfortran, up-to-date status of the compiler, recently fixed bugs, etc. You can find here our "getting started" web page for new users of gfortran.
Eclipse is an open-source community project that is focused on building an extensible development platform: a suite of software tools that assist in the writing of software. Primarily it is used as a Java integrated development environment (IDE) but has been adapted for many other languages including python, C, C++, and FORTRAN.
The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. At present, it provides C and Fortran77 interfaces to a portably efficient BLAS implementation, as well as a few routines from LAPACK.
MOPAC (Molecular Orbital PACkage) is a semiempirical quantum chemistry program based on Dewar and Thiel's NDDO approximation. Available at this site are the open source version (OpenMOPAC) and information on the commerical version.