As other free projects, OpenLayers is also characterized by a very active and open community of users and developers. Beyond the access to the source code, a lot of documentation, tips, and user recipes can be found at the official website and the various community channels.
Site: http://openlayers.org/
Documentation and Wiki: http://trac.openlayers.org/wiki/Documentation
Code repository: https://github.com/openlayers/openlayers
Examples: http://dev.openlayers.org/releases/OpenLayers-2.12/examples/
Official mailing list: http://trac.osgeo.org/openlayers/wiki/MailingLists
Official IRC channel: irc://irc.freenode.net/#openlayers
User recipes: http://trac.osgeo.org/openlayers/wiki/UserRecipes
User FAQs: http://trac.osgeo.org/openlayers/wiki/FrequentlyAskedQuestions