I keep most of my software on my Github page. I prefer to program in C, Python (Numpy, Scipy, Matplotlib) and CUDA. All projects are free software, licensed under the GNU GPL v3. My favorite projects are:

A GPU-based 3d discrete-element granular dynamics simulator with optional coupling to Navier-Stokes or Darcian pore fluids.

A 2d discrete-element granular dynamics simulator for simulating sea-ice dynamics, with optional coupling to ocean and atmosphere models.

A simple 2d DEM code for educational purposes.

An introduction to Git version control.

A 3d lattice-Boltzmann code to approximate the Navier-Stokes equations of incompressible fluid flow.

Configuration files for my favorite pieces of software: vim, tmux, zsh, X11, i3, mutt, ...

A command line musical synthesizer following the POSIX philosophy.

Simple model of aeolian sand erosion, transport and deposition.

Markov-Chain Monte Carlo age and erosion rate inversion from cosmogenic nuclide concentrations (source).