This gist was a result of an answer I posted at blender.stackexchange.com (http://blender.stackexchange.com/questions/461/how-to-set-a-property-value-in-blender-game-engine/501#501)

blender_game_engine_basics_v1.py

import bge

controller = bge.logic.getCurrentController()
sensor = controller.sensors['up_WKEY']

if sensor.getKeyStatus(bge.events.WKEY) == bge.logic.KX_INPUT_JUST_ACTIVATED:
    owner = controller.owner
    actuator = controller.actuators['upkeycount']
    actuator.value = str(owner.get(actuator.propName) + 1)
    controller.activate(actuator)

blender_game_engine_basics_v2.py

import bge

controller = bge.logic.getCurrentController()
sensor = controller.sensors['up_WKEY']

event = sensor.events[0]

key, status = event

if key == bge.events.WKEY and status == bge.logic.KX_INPUT_JUST_ACTIVATED:
    owner = controller.owner
    actuator = controller.actuators['upkeycount']
    actuator.value = str(owner.get(actuator.propName) + 1)
    controller.activate(actuator)

blender_game_engine_basics_v3.py

import bge

controller = bge.logic.getCurrentController()
sensor = controller.sensors['up_WKEY']

if [bge.events.WKEY, bge.logic.KX_INPUT_JUST_ACTIVATED] in sensor.events:
    owner = controller.owner
    actuator = controller.actuators['upkeycount']
    actuator.value = str(owner.get(actuator.propName) + 1)
    controller.activate(actuator)

blender_game_engine_basics_v4.py

import bge

controller = bge.logic.getCurrentController()
sensor = controller.sensors['up_WKEY']

pairs = []
pairs.append([bge.events.WKEY, bge.logic.KX_INPUT_JUST_ACTIVATED])
pairs.append([bge.events.WKEY, bge.logic.KX_INPUT_ACTIVE])

go = any([pair in sensor.events for pair in pairs])

if go: 
    owner = controller.owner
    actuator = controller.actuators['upkeycount']
    actuator.value = str(owner.get(actuator.propName) + 1)
    controller.activate(actuator)

blender_game_engine_basics_v5.py

import bge

controller = bge.logic.getCurrentController()
sensor = controller.sensors['up_WKEY']

inputStatuses = [bge.logic.KX_INPUT_JUST_ACTIVATED, bge.logic.KX_INPUT_ACTIVE]
pairs = list(zip([bge.events.WKEY]*len(inputStatuses), inputStatuses))

go = any(list(list(pair) in sensor.events for pair in pairs))

if go: 
    owner = controller.owner
    actuator = controller.actuators['upkeycount']
    actuator.value = str(owner.get(actuator.propName) + 1)
    controller.activate(actuator)

Blender Demo : Game Engine : Logic Bricks + Python Side-by-Side

http://www.youtube.com/watch?v=UL0_I7iFlbU