I have to keep things in particular places. I used to be really bad about losing things as a kid, and this is my copying mechanism, which has turned me a little bit OCD.
For instance, I always know where my keys are, because there are only 3 places they will EVER be - in the ignition of my car, on the front right corner of my dresser, or in my from left pants/shorts pocket. When I stay at a hotel, I always have to pick a spot when I first arrive to be my designated place to put down my keys, wallet, cell phone, etc when they aren't in my pockets. Usually that spot is the front corner of the hotel room's desk, either on the left or right side of the desk, depending on which is closer to the center of the room. And each item has particular pockets where I always carry them - keys in front left, cell in front right, and wallet in back right. Loose change always goes in the front left with the keys, but I usually empty my pockets of change as soon as possible - I have change bins on my desk at work and my dresser at home for accumulating coins.
Another example is that when I load my dishwasher, I always group the silverware together by type in the silverware holder. So all my forks are in one spot, the big spoons are together, the little spoons are together, etc.
And my apartment always looks tidy at first glance, even though I don't clean often enough, just because I always put things in their place. I don't have papers all over the place - they're all in one stack. The same with my desk at work, actually. The stack of papers closest to my computer at the office is my hot "to do" stack, then a little further away is a less hot "to do" stack, etc.
I really don't think I'm OCD, though. I do this stuff out of habit, to help my mind keep track of things, but if something's out of place, I don't really freak about it and rush to fix it.