Open-source software I've been working on during the past years.
Homepage: http://decibel.silent-blade.org
Decibel is a GTK+ open-source audio player designed for GNU/Linux, which aims at being very straightforward to use by mean of a very clean and user friendly interface. It is written in Python and available in some official repositories (Debian, Ubuntu).

Homepage: http://pypar2.silent-blade.org
PyPar2 is a Linux graphical frontend for the par2 utility. It is written in Python and uses the PyGTK library. PyPar2 is available in the repositories of many well-known Linux distributions (e.g., Debian, Ubuntu, Fedora).

Homepage: http://fahmon.net
FahMon is an open-source tool which allows users to easily monitor their Folding@Home clients. It is written in C++, uses the wxWidgets library and exists for both Linux and Windows.
Please note that I am no longer the maintainer of FahMon since version 2.2.0. I chose to let someone else take over in order to have more time for other projects.
Homepage: http://nota.silent-blade.org
Nota is a small open-source todo manager for Linux. It is written in Python and uses the PyGTK library.

Homepage: http://sensorscope.epfl.ch/index.php/Network_Code
This stack, featuring multi-hop routing and synchronized duty cycling, has been developed for SensorScope during my postdoctoral position at EPFL. It is written in NesC for TinyOS 2.x.
Homepage: http://sensorscope.epfl.ch/index.php/TinyOS_Watchdog
Homepage: IM Status
This is a plugin for Exaile media player which updates the online status of your instant messenger client according to the music you are listening to.

Homepage: ExtListView
This is a class that inherits from a TreeView and that provides an easier API than the standard TreeView.
I have contributed to some open source projects through patches: Comix, Compiz, Vim.