Just stumbled upon this thread. Collecting passport stamps has been my hobby!
I guess the number of countries I've visited really depends on how a country is defined.
According to TCC (Travelers century club): 189
According to World66.com: 155
According to Passportstamp.com: 166
UN members: 138
My World66.com map
My Passportstamp.com map
My TravBuddy map