Should everything DO provides be FREE? If not, how does DO charge? If so, how is DO sustained?

We have a strong feeling that it should be free but we recognize a need for funding to maintain infrastructure. The content and services should be provided for free. We need to consider various successful models (MoveOn, Facebook) to get ideas. We don't want to rule out having providers (that are users of the system) that charge for their services. This needs to be reviewed.