Denizens of the Internet hate slideshows. They don't want to click through 100 different pages to get information that could, technically, be placed on one. It's often done just to drive up page views and ad rates, readers know that, and readers hate it.
I have a use for them, though: Sporcle quizzes. Yep, it's Sporcle day.
Here's what's going to happen. You're going to be shown one national flag. You are to identify that flag. Then a second flag will be provided to you, and you will be shown only one flag at a time in rapid-fire fashion. You are to then identify that second flag. A third flag will then be added, then a fourth, and on like that until you are trying to pick out the newest flag in a rapid-fire 20-flag slideshow. You will have three minutes to complete the task; I finished with 52 seconds left on the clock.
If you don't want a rapid-fire slideshow, you might also try this quiz. Here you'll be given maps of unusual or disputed borders and you have to identify the countries they belong to; you'll have nine minutes to get through 15 of them.
Or this slideshow of maps of American wars; this is five minutes for 12 wars.