GPF General Purpose Fortran repository. Modules for basic access to POSIX system functions, date and time representation, command argument parsing, Fortran preprocessor/unit tester/code-document integration, … including example programs that exercise the modules.
JAMS - a collection of general Fortran modules offering miscellaneous functions in the categories Computational, Date and Time, Input / Output, Math / Numerics, Screening, Sensitivity Analysis and Optimising / Fitting, and Miscellaneous. Written by Matthias Cuntz, Juliane Mai and Stephan Thober. (OS: MIT)
MGNet - repository for information related to multigrid, multilevel, multiscale, aggregation, defect correction, and domain decomposition methods.
Collected Algorithms (CALGO) from ACM - Software associated with papers published in the Transactions on Mathematical Software, as well as other ACM journals are incorporated in CALGO. This software is refereed for originality, accuracy, robustness, completeness, portability, and lasting value.
ASCL.net: Astrophysics Source Code Library - free online registry for source codes of interest to astronomers and astrophysicists, including solar system astronomers, and lists codes that have been used in research that has appeared in, or been submitted to, peer-reviewed publications.