The best way to prepare for applying for mentoring programs like GSoC in the future is to become a contributor of the project that interests you ahead of time. The links below link to pages with some nice folks in each organization who can help you make your first contribution any time throughout the year.
Once you decide what project you are interested in contributing to and explore the information available about that project on its website and wiki, you can introduce yourself to the project's mentor and ask them any questions you have about contributing to the project. The mentor can help you build the project's code, identify an easy bug to start with, and help you with your patch for that bug. The mentor can guide you through your subsequent contributions and point to the resources for solving a particular task.
IRC is one of the main communication channels for open source projects. You should try contacting a mentor in the project's IRC channel, and use e-mail if you don't see them on IRC. Typically, there are other people in the project's IRC channel, who can help you too. You can address the mentor directly in the IRC channel by using their nick in your question. E.g. if the mentor's IRC nick is kelly, you can say "kelly: hi! I just built project-foo and looking for a bug to fix - I found bug 1234 and bug 4321 in the project's bug tracking system that both look like something I can try to work on, but I wanted to see if you have any recommendation, since you are listed as a mentor for the project".
There are thousands of open source organizations out there, and hundreds of them participated in GSoC in the past. For example, the full list of organizations that participated in 2011 is here.
Please don't hesitate to explore an organization not listed on this page. Chances are you will find some clues about how to get involved on that organization's homepage. One approach is to look at the commit log of the project within that organization that interests you to see who are its most frequent contributors and follow their posts on the project's IRC channel and mailing list to learn more about the project. You can also ask any questions you have on the project's IRC channel and mailing list.
You can find more mentors, easy bugs, and things to learn on the OpenHatch community site. In particular, OpenHatch training missions are useful to complete for anyone new to contributing to open source.
The organizations that will participate in GSoC in 2012 will be announced on March 16, but even if you start out contributing to an organization that happens to not be part of GSoC this year, you will still be much better prepared to apply to a different organization that will participate in GSoC.
Organizations that are interested in providing one-on-one mentors year round can be added to the list by e-mailing Marina Zhurakhinskaya (marinazik at gmail) with a link to their list of mentors and a brief description.
Please help spread the word about this resource by sending a provided e-mail to student groups, posting a status update on social networks, or distributing the flyer and the leaflet with the information seen on this page.
- Ankur.org.in mentors - Ankur.org.in is a group of volunteers who collaborate to promote localization and internationalization with the specific aim of improving usage of Bengali in Free and Open Source Software projects. Projects include translation, content development, and development of tools, utilities, widgets and APIs that help the localization effort.
- Apache Software Foundation mentors - The Apache Software Foundation is an umbrella organization for a broad range of open source software projects. Through a collaborative and meritocratic development process, Apache projects deliver enterprise-grade, freely available software products that attract large communities of users.
- Apertium mentors - The Apertium project provides a platform for making free and open source rule-based machine translation systems. There are currently around 30 language pairs, with several being unique to Apertium: Breton, Occitan, Asturian and Aragonese.
- Battle for Wesnoth mentors - Battle for Wesnoth is an open source, turn based strategy game in a medieval-fantasy setting. It is mature project with continuing active development and frequent improvements.
- BRL-CAD mentors - BRL-CAD is a powerful cross-platform open source solid modeling system that includes interactive geometry editing, high-performance ray-tracing for rendering and geometric analysis, image and signal-processing tools, a system performance analysis benchmark suite, libraries for robust geometric representation, with more than 20 years of active development.
- Debian mentors - Debian is a free GNU/Linux operating system. It comes with over 29000 optional packages of precompiled software bundled up in a nice format for easy installation.
- GNOME mentors - GNOME offers an easy to understand desktop for GNU/Linux and UNIX. It is also as an umbrella project for many applications that people use on their desktops, such as Empathy, Pitivi, gedit, and others.
- KDE mentors - The KDE Community is dedicated to creating a free and user-friendly computing experience, offering an advanced graphical desktop, a wide variety of applications for communication, work, education and entertainment and a platform to easily build new applications upon.
- LibreOffice mentors - LibreOffice is the power-packed free, libre and open source personal productivity suite for Windows, Macintosh and GNU/Linux. It provides six feature-rich applications for all your document production and data processing needs: Writer, Calc, Impress, Draw, Math and Base.
- Mozilla mentors - Mozilla is dedicated to putting you in control of your online experience and shaping the future of the web for the public good with products like the Firefox web browser.
- NESCent mentors - NESCent (the National Evolutionary Synthesis Center) is an umbrella organization for open source projects related to computational evolutionary biology. The projects use a wide variety of programming languages.
- NRNB mentors - NRNB (the National Resource for Network Biology) develops free and open source software to support network biology research. The projects include network visualization and analysis tools like Cytoscape (Java) and collaborative pathway resources like WikiPathways (Java, PHP).
- OpenHatch mentors - OpenHatch is an open source project with the goals of lowering the barriers to entry into open source contribution and increasing diversity. It provides training missions, IRC help, outreach events, and a way to find bugs from various projects.
- Python mentors - Python is a widely-used open source programming language. Working on CPython you would be improving the most popular Python implementation, its documentation and its standard library.
- RTEMS mentors - RTEMS (Real-Time Executive for Multiprocessor Systems) is a free real-time operating system designed for deeply embedded systems including automotive, medical devices, science, industrial control, and space flight. RTEMS has been to Venus, circles Mars, is going to the asteroid belt, and can be found in high energy physics research labs around the world.