FLICK TO NUDGE
WHAT
A slight flick of the index finger in any direction moves either the screen itself or a selected object in that direction.
USE WHEN
Use Flick to Nudge for simple drag-and-drop, to push objects away (or off-screen), or for slider movements.
If the "object" is the entire screen or a list, the related pattern is Fling to Scroll.
WHY
Since grasping and moving aren't possible with a 2D screen, flicking is a natural gesture for moving items around the screen.
HOW
The index finger lightly touches the screen and moves in a straight line in one direction. If the tip of the finger is used, it can indicate a light flick, whereas the use of a finger pad (combined with a longer duration) can indicate more of a push or pull. (Objects on-screen can react differently to both.)
One addition to this is physics to mimic slowing to a stop. Based on the speed of the flick, the movement of the object will continue after the gesture is complete, slowing to a gentle stop. The rate of the flick is translated into momentum, which is slowed and eventually stopped by simulated friction.
EXAMPLES

Figure 3-19. The Neonode N2, using the NeNo user interface, is controlled by a series of Flick to Nudge gestures along a set of marked UI controls. Courtesy Neonode.

Figure 3-20. The HTC Diamond allows users to ...