How do we make money?

I've been thinking about community revenue models.  What works best for different types of communities.  I think freemium is the obvious choice for a lot of people.  Pay for t-shirts or other items as a fundraiser, use those items as a premium for an annual fundraiser.  Beyond that?  Maybe offer a class/webinar that would be of value to a subset of your members.  I wonder what else will come to mind at 3 in the morning.  We talk a lot about proving ROI to our employers.  But what about when the community is the business?  Can you make a community self sustaining financially without bombarding your members with ads?