Simcoe County Maps 

http://simcoe.ca/dpt/it/gis/index.htm

  These Simoce County GIS Maps are some of the best out there.  Great high res satellite shots.  Property line boundaries.  Current MLS listings. Layers and much more.   

I often use the Easy Map Viewer.  Its loads quick and shows everything I need.  The measure and draw tools are great for approximating property boundary lengths.