In a world of almost seven billion people, "current events" happen all the time. Sometimes they happen so quickly it's impossible to try to take advantage of it and monetize it. But if you can stay in the money-making mind-set when you're reading or watching the news, you could easily grab a new stream of passive income.
For example, Iran is in the news this week because they are testing their missiles. North Korea was in the news last year for doing the same thing. If you happened to run a blog about missiles or North Korea last year, you probably substantial boost of traffic for a couple weeks. The same should be true today if you have a website about missiles and / or Iran. But that traffic will probably be short-lived (ask the guy who runs the missile / North Korea blog), so it might be better to "capture" a current event.
What do I mean by "capture" an event? For example, the legendary George Carlin died last month. If I was a huge fan of George Carlin's (which I am), I could register GeorgeCarlinMemorial.com (which is available at the time of this writing) and put together a bunch of videos and pictures to remember him. A cynic might say you're trying to make money from his death, but that's just cynical because you wouldn't be exploiting his death. Even though more people will be using the keyword "memorial" when they search for George Carlin.
That is just one example. Another would be, say, the Iraq war. If you were to land the domain name IraqWar.com right when the news broke, you could probably retire today.
Even though big things happen every day, you can't usually build an entire blog around that event. When you capture an event, it has to be big and you have to do it quick. Otherwise you wont get the key domain name, or that event will soon me forgotten by the world.