Looking into this further,  the SalesForce non-profit starter pack deals with Donors and Donations.

A typical issue when dealing with donors is that you often want to track relationships between different donors; for example spouses in the same household who contribute independently to your organization. One way of doing this (not just in SalesForce) is the notion of a household.  In database terms, a household would represent many-to-one relationship where a one or more contacts are members of a single household.

SalesForce will accommodate no less than 4 different kinds of contact/account models. The details are explained in their FAQ about account models.  The upshot is that out of the box, the most recent version of their non-profit starter pack uses what they call their household model.

If you check out the terminology in the diagram above, you can see that they are mapping non-profit terminology to their sales terminology.

We’ll have to look at this when it is wired up as a online form.