Others:
Denmark
Norway
Finland
Estonia
Latvia
Lithuania
The Soviet Union
Luxembourg
The Vatican
You were in the Iraqi army?
Oops, forgot to include Ireland in my “others.” I’m hoping to add the Netherlands to my list in June. I’ve been to the airport there but that doesn’t count.
You really should have added Norway if only because of the ratio of hot women. When I was in Narvik they must have been having a blonde convention or something. 
Unfortunately, I couldn’t find a Wikipedia article listing the ratio of hot women in various countries, so I had to settle on population, even though I knew it would not correlate perfectly with whether places get visited by Dopers.
Some time this weekend, I’ll go through all the replies, and give a list of the “other” countries – even the Vatican, though it didn’t look like a real country when I visited there nearly 50 years ago (no immigration control, no customs, no border fence: you just walk into St Peter’s Square, and you’ve left Italy 
– the only thing telling you that it’s a different country is that they have their own stamps).
Shhh!
Canada
Germany
Italy
Austria
Netherlands
U.K.
Switzerland
Iraq (if a war counts as a “visit”)
Saudi Arabia
Not on your list:
Qatar
Kuwait
They’re included in The Netherlands. Similarly, the overseas regions of Martinique and Guadeloupe (as well as French Guiana and Réunion) are just as much integral parts of France as Hawaii is of the USA.
Kuwait
Oman
United Arab Emirates
Bahrain
The above, plus
Barbados
Cook Islands
Cyprus
Dominica
Ireland
Luxembourg
New Zealand
Oman
St. Lucia
UAE
Vatican City