If you found a problem with one of the packages and want to report a bug, this already counts as a useful contribution. The majority of our projects has an issue tracker, and if one is missing you can still send us the bug report via mail.
If you can provide patches, we are also very happy to incorporate them for fixes and new features. All of our projects are either using Mercurial or Git. Just fork the project of choice on github or bitbucket, and send us a pull request. For some patches it might be necessary to discuss the changes, so be sure to reach out to us on the :ref:`irc-channel` or one of the mailinglists.
When contributing patches, make sure to follow the :ref:`Pocoo Style Guide <styleguide>`.