We have a couple (one with land and one dwelling, one with land and a duplex). The land is assessed and taxed to Habitat for Humanity, and the buildings are taxed to the residents. We use an economic obsolescence on the dwellings to decrease the assessed value. There are no adjustments to the land, and are currently billed at a regular house-site value.
We have the land coded for standard residential, and the use for the dwelling is residential building/leased land.
Hope this helps!