Over the last few years, my interest and involvment in open-source projects have evolved:

Desktop years

Between 2005 and 2007, I was mostly involved in Ubuntu, and contributed to packaging KDE apps for Kubuntu and administrating revu (RIP);

Sysadmin years

I started working as a sysadmin in 2006, and since then focused my contribution more on server-side code.

Augeas

I have been involved in the Augeas project since 2007. My work in Augeas has been mostly to write lenses for common Unix configuration files. As such, my main language of contribution has been the Augeas language itself.

Over the last few years, I also added C code to this project, the main part being the XML export API call.

I maintain Augeas packages in Ubuntu (and a PPA for new versions).

In 2011, I have begun writing an open-source book about Augeas, which is still a work in progress.

Perl

In the first company where I worked as a sysadmin, Perl was used a lot (now it's mostly Ruby). I got used to writing tools (and sometimes whole programs) in Perl, some of which I contributed back to the CPAN:

Config::Augeas::Exporter, a module to export the Augeas to various format. This was mostly used as a prototype for the XML export API call in Augeas, now rewritten in C;
Config::Augeas::Validator, a tool to validate configuration files using Augeas. I plan to port this to Ruby and integrate it in Puppet;
Config::KingKong, a simple templating tool to generate configuration files;
Reprepro::Uploaders, a module that emulates reprepro upload rights.

Since 2011, I also co-maintain the Config::Augeas module (Perl bindings for Augeas) with Dominique Dumont.

Another Perl project, Diathica is a Twitter/Identica Bible bot.

Puppet

I have been interested in Puppet since 2006. The company I worked for at the time was not interested in replacing Cfengine with it, so I mostly played with it on my own.

Since April 2012, I have the pleasure of working for a company that has been using Puppet for years, and knows the value of contributing back.

For this reason, I am recently contributing more and more Puppet code through my daily sysadmin hacking.

LaTeX

I started translating books and publishing them in 2011. The more I dove into LaTeX, the more I enjoyed the power of it. On my path to publishing, I released a few modules to CTAN:

fancytabs was created to add shaded smart tabs to a book I am in the process of publishing;
fontbook helps to generate a font book in XeTeX/LuaTeX;
impnattypo implements French typography recommendations, making heavy use of LuaTeX;
moderntimeline is an extension to moderncv that provides timeline support in a CV;
nowidow provides helpers to manage widows and orphans;
babyloniannum implements Babylonian numerals;
coloredlettrine is an attempt to create bicolor initials using LaTeX and the EB Garamond font.

Most of these packages were implemented as answers to questions on tex.stackexchange.com, either my own questions or other people's.

I also co-maintain the bibleref-french package with Maïeul Rouquette.

Wave

In 2008, Google opened Wave and I found this platform really interesting. I wrote a few robots and extensions for it:

Flammard, a Bible bot;
Annoty, a generic, programmable, annotations bot.

Others

I enjoy hacking programs that I find interesting and/or useful. When I find one that does almost what I'd like to achieve, I'm more than happy to contribute back my hacks. Git and github have tremendously made this easier, so it's become a habbit to fork and request merges. Such small contributions include: