I work for a municipal services district that takes care of the unincorporated townships in the county. We represent them like any incorporated city.
If a resident comes to us for a parcel address change, we file the change of address affidavit directly with the County Recorders office. It's a fairly simple procedure. Once it's recorded the other county entities like Assessor, Treasurer, etc are notified via the Recorders office.
For assigning addresses in new developments, we have deployed the ESRI Address Data Management Solution.
That should just about do it....