Cool internet feature I found. Allows you to create your own custom map of countries and states you've visited.
Here's my world map:
create your own visited countries map
And here's my U.S. map:
create your own visited states map
I admit, I may not be perfect in my recollections of where I've been, but my mistakes are mistakes of omission.
And here are the countries in Europe I've visited:
create your personalized map of europe