As mentioned on my GLSC and GCIH pages, the SANS community is incredible. It’s harder to define than other communities, as there isn’t a single “home”. Though much of the activity occurs on the Advisory Board mailing list, some of it occurs on other mailing lists focused on penetration testing and teaching. Some community members email back and forth and others hang out on various channels on IRC. Of course, there is a substantial portion of the community that interacts at the annual SANS conferences.
This community is highly supportive and everyone helps out everyone else. If you have an opportunity to join, I strongly recommend that you do so. Common ways to join this community involve taking a class or scoring highly on a test.