I'm helping to organize an 'intro to FLOSS' orientation module for new hires at the WMF with Tomasz Finc, and we're curious to know what all the projects are that the we collaborate with/contribute to. Just from my own experience working at the WMF, I know of a handful like Drupal, CiviCRM, Phonegap, Varnish, jQuery, Squid, Open Stack... but I'm very curious to know the others.
Thanks!