I'll briefly describe a rather different sort of meditation, with the goal of discovering whether Theravadins ever practice anything similar; or if it's even compatible with Theravada.
Some of the best mediaeval Samurais had a preternatural ability to sense danger before any of their five senses could alert them. Even to the point where others thought they had mind-reading magical abilities. But in reality, it was the opposite. It was a primal ability, which most animals have, but which most humans have become blunted to. Here's a type of meditation that cultivates it. Twenty minutes a day (or less), if done consistently, can lead to amazing situational awareness.
1. Be in a completely familiar place (for me, it's the master bathroom); keep your eyes open and feel free to look around.
2. Completely still all thoughts, as you would in other types of meditation (i.e. block out what happened at the office today, your weekend plans, etc...).
3. Focus only on the sights and sounds around you. Since you're in a very mundane, totally familiar place, this will be initially very annoying. Is the towel hung totally straight, or is it a bit tilted to the left? Memorize it. How much of the toilet paper roll remains? Is the bar of soap halfway finished, almost new, or what? As for sounds, what do you hear? If the window is open, there's plenty to hear, from car engines to birds.
4. The above subjects (only that which is immediately in your view and hearing) are the only things you can think about. Like I said, it's really annoying for a while.
5. If you continue this way for at least ten minutes, you'll be living solely in the moment, in your direct environment. This is much more akin to how dogs and cats 'think' than to how gods think.
6. Your sense of hearing and sight will soon dramatically increase. For example, the voices coming from the house across the park. Instead of just voices, you begin to identify specifics: "A woman, probably in her 40s." "An older man." "And a boy, probably in his mid teens." Same with other sounds. Instead of just generally hearing a car drive by it becomes specific: "A diesel Hindustan Ambassador, probably about ten years old." And etc...
7. After having done this for a week or so, take it outside with you the next time you walk down a city street. Don't walk around with a billion thoughts and worries swarming through your head. And don't use your iPod. Instead, focus only on who/what you see, hear and smell immediately around you; in the exact moment.
This leads to a heightened sense of awareness. People can learn to sense danger before it comes, and act accordingly; or to sense safety. After a while, you might even begin to feel the intentions of those you're with, whether good or bad. (But if you're naturally paranoid it won't work, because you'll always assume the bad). And, if you take this sort of mindfulness with you into a karate or Muay Thai match, remaining totally relaxed yet highly alert, you gain a huge edge over your opponent. If you're in the military, it might enable you to save your own life and the lives of your squad.
(Dogs have this ability naturally, since their minds aren't swarming with a zillion ideas and worries. They're constantly living in the moment, which enables them to constantly feel their environment.)
Since it was the Samurai who perfected this art, it's most likely more related to Zen. Do Theravada monks ever do anything similar?
"You're a poor farmer, mind of mine!
You've let the precious field of human life sit fallow too long.
If only you had planted right, a golden crop would be yours by now!"