There is a lot of controversy lately in American Unitarian Universalist circles after the publication of an extensive survey on religious affiliation in America by the Pew Forum on Religion. Among those who have commented (and generated many thoughtful responses) those data in their blogs, I recommend reading Philocrites, Peacebang, Surviving the Workday, and Transient and Permanent.
Basically, what the Pew Forum survey results seem to imply is that there are many more Unitarian Universalists who are not affiliated to any UU congregation, than those who are actual members of congregations. The survey has found that 0.3% of Americans identify themselves as Unitarian Universalists, which is roughtly equivalent to 600,000 people out of the total population of the USA, but the total adult membership of UU congregations is about 160,000.
These data raises questions about how to serve those who are not regular attendants or even paying members of Unitarian+Universalist congregations. The issue is probably not just American but it may be applied, in different degrees, to other countries. How many Britons would identify with Unitarian beliefs and principles, but simply dislike the idea of going to church on Sunday morning? How can emerging Unitarian groups in Europe, Latin America, Africa, etc. reach out to those who agree with Unitarians but disagree with "religion"?
And finally, we tend to identify members with those who sign a book, or get baptized, or pay their membership fees. Perhaps a wider discussion on membership and belonging is in order, so that we can provide spiritual services and focus on those who are away from our religious center. Remember the Gospel parable about the shepherd and the sheep?