Community Surface Dynamics Modeling System: The Community Surface Dynamics Modeling System (CSDMS) deals with the Earth’s surface — the ever-changing, dynamic interface between lithosphere, hydrosphere, cryosphere, and atmosphere. We are a diverse community of experts promoting the modeling of earth surface processes by developing, supporting, and disseminating integrated software modules that predict the movement of fluids, and the flux (production, erosion, transport, and deposition) of sediment and solutes in landscapes and their sedimentary basins.
Geomorphtools.org: A site developed to publish and distribute software, codes, and tutorials that assist in digital topographic analysis.
GIS 4 Geomorphology: The site provides a growing set of how-to instructions on many things geologists want to do in GIS.
Landlab: A Python based toolkit for landscape evolution modeling.
LSDTopoTools: Open-source package for DEM analysis and landscape evolution modeling.
TopoToolbox: A MATLAB program providing many tools for DEM analysis. (Check out the Topographic Analysis Kit for TopoToolbox as well)