I've been digitizing a lot of building footprints and parking lots in the last week or so, in preparation for an upcoming mapping party in Falls Church, VA. User OpenBrian has advocated this technique as a means for making the editing/tagging phase of the mapping party more productive. The theory (I think) is that it simplifies the process of transfering field notes onto some pre-existing geometric shape. I'm beginning to see that it maximizes the effectiveness of arm-chair mapping as well, since even the most familiar of landscapes have easily-overlooked details that require a site visit.
So, to test this out I've added a considerable amount of detail to commercial and institutional buildings along Lee Highway starting in Falls Church and proceeding east into Arlington. I typically add the building footprint, adjacent parking lots and parking aisles. Later I'll add business/institutional names, addresses, and other useful information as time permits, typically one or two at a time.