Just like the title says, would be nice to able to import shapefiles or KMZ files as overlays into completed maps.
What kind of content are you wanting to coordinate?
Mainly thinking drop property and permit boundaries on it.
You might check out mygeodata.com and gisconvert.com to see if (for now) you can turn those GIS and Google Earth files into PDFs that you can overlay. The plats should definitely already be available in PDF. QGIS is also another great resource for parcel data.