Short answer: formal viewpoint. Or a functional mentality.
For example, last year, I saw Forbes Magazine with cover article about how al-Qaeda was losing money, and it suggested that Osama "needed a new business model."
I can not make this stuff up.
The point is, people look at things from a “formal viewpoint.” I would look at a large pile of money and think of where a character would hide it. An accountant would probably count it all. A pyromaniac would look at it as stuff to burn.
In my case... to use an example, in 1998, my family went to London and stopped off to see the Crown Jewels. Everyone else stared at the jewels. I went and looked at the security. I didn't take notes, since I didn't want to be thrown out of the Tower of London by the fastest possible route [the jewels were a few floors up]. The British Museum got the same treatment from me -- The Elgin Marbles from the Greek Parthenon had their own wing.... so, if the Greeks really wanted them back, they could steal them with a few construction helicopters and just airlift the whole wing—the Israelis did that with an Egyptian radar tower once to great effect.
Basically, it's a matter of looking at things from a certain viewpoint. I suspect that if I go see the Mona Lisa, the majority of my time will be pondering how someone could disable the security guards, the electronic surveillance, and walk away with a few paintings from the Louvre. Though the answer would probably be to steal something from the basement storage area—less security, without the individual alarms on every piece.... hmm, now that's an idea....can someone scan for Semtex at the entrypoint to the Louvre? Hrm...
The sad thing is that the above was really thought up as I wrote it.
[More below the break]
I created one character because a teacher in high school, on the first day of class, said “I'm a wanted terrorist. I've been hunted for 19 years.... I can kill you with two fingers.” He was the creative writing teacher, so we went with it....
And I wondered... “What if he was telling the truth?”
He's in a back pocket somewhere, for when I get around to writing that novel. The annoying thing is, I have it outlined....
Some, like Harlan Ellison, have described writing as a compulsion, and that's because that's how we seem to be wired. Be it the Tower of London or the British Museum, writers wonder how we can do something with where we are, what we're doing, some little factoid we picked up, or a stray comment.
I don't think I've ever gone to someplace and not wondered how to blow it up, shoot it up, or what would be required to do something like that.
With A Pius Man, Scott “Mossad” Murphy came out of the mass of Evangelicals flocking to Israel after 9-11. What does Israel do with all of these meshuge goyim? And what do you do with them if they want to join the military, or even the intelligence services? Answer: the goyim brigade—Mossad agents who not only "don't look Jewish," but aren't. Murphy was just a throwaway character I had come up with to use “someday.” He had literally been shoved into a notebook and left there for three years. I had used him once as a supporting character in one book, and all but forgot him. Later, he came in handy.
And that's why writers have notebooks—to keep track of all the random neurons firing off with ideas. You never know when there's going to be something that comes in handy. Stephen King supposedly has a trunk filled with notebooks of ideas past.
So, if you ever think that a writer is odd, well, they are. They look at things from different points of view—if only because they have to be able to see things from the points of view of different people as they write them. Stephen King writes about things that scare him... and that seems to be everything... I think up various and sundry ways to kill someone with a ballpoint pen (I'm on nine).
That's how we find ideas. We're wired to.
But then again, who'd go into this profession if we weren't?