Well said, Matt.
Especially the part about participating in an exchange. The Blind Print Exchange is the highlight of my own APUG participation. As anyone who has received something from me can attest, I throw myself into that activity at a level wildly out of proportion to any inherent value in my rather pedestrian photos. But there's no better way, I think, to get a sense of what this community is all about than to send and receive real photographs that you've made yourself, or that have been made for you by someone else.