Who owns a nonprofit organization?
This is a nice article on a pretty important topic...
Donor Power Blog: Who owns a nonprofit organization?
Includes some links to other articles about this same issue.
From my perspective, a non-profit organization is owned by the entire community: not just those who invest in it or those who use its services. That's why I believe it is so critical for organizations to be transparent with their financials, open about their struggles/successes and committed to partnerships with other non-profits, as well as business and individuals (particularly clients).