Usually you can be helpful by just responding to questions on the email@example.com list. Often we have new users who need some guidance with simple tasks like installing properly or proper coding of a program. You can help answer those questions.
Supplying patches for newer versions of the Windows API and submitting them on the SF project Tracker can help improve MinGW.org and help others take advantage of those new API as well. Be sure to use msdn.microsoft.com as your source for those new API because without publicly available documentation we cannot accept those patches. Do not refer to the SDK source when writing your patch or submitting it to the Tracker item for review. Do refer to the MSDN page where you found your documentation for your patch.
Reviewing the wiki documentation and providing updates or new pages based on recently frequently asked questions on the list is also beneficial. We have a hard time keeping up with the documentation and anyone who has small amounts of time to improve it are welcome to do so.
The site CMS software is Drupal and we are looking for talented persons who can keep this software updated on a regular basis. This includes the main Drupal core software as well as contributed modules that are used. The software itself will give you hints as to what needs to be updated given an appropriate role for the user.
The site DB software is MySQL and persons talented in maintaining performance and backup are needed. While the hosting provider is doing a great job with backups we shouldn't really depend on their effort since we are getting the hosting for free and having a separate backup process would allow us to move providers should we need to do so.
The server is an Ubuntu server and persons talented in keeping the system maintained and the file systems backed up would be beneficial. We added services to the base system and we need to keep those and the base system up-to-date.
Of course access to the host to maintain the software, the database and the server comes with a price caveat of trust. We may need to see references from others that can vouch for your work. It is a paranoid world and we need to live in it. If you find yourself wanting to take care of any of these system tasks then send mail to mingw-users-owner at list dot sourceforge dot net and we will get back to you.