Everywhere I've ever traveled, the most I've ever needed is a passport. Well, that's not entirely true; when I was on a cruise stop in St. Petersburg over 3 years ago, merely to get off the ship and go on a tour required a visa (that took about 10 minutes to obtain after standing in a long line). But I've never gone anywhere that I even considered might require a visa. Then I saw this list.
There are several countries there that are on my "go to eventually" list, including Nepal, Australia, Madagascar, Jordan, and Vietnam, that require visas from American travelers.
Given their proximity to the Emirates, I was surprised about Qatar and Oman. Brazil and India were also somewhat of a shock.